5.4. Excited States Calculations¶
A plethora of methods to compute excited states exists in ORCA. Here we give a brief overview of the main methods, with focus on the basic usage and current capabilities of each. Detailed documentation for each method is indicated in each subsection.
Multi-reference methods, such as NEVPT2 or MRCI, are described elsewhere (N-Electron Valence State Perturbation Theory (NEVPT2), Multireference Configuration Interaction and Pertubation Theory (uncontracted)) in the manual.
5.4.1. Excited States with RPA, CIS, TD-DFT and SF-TDA¶
ORCA features a module to perform TD-DFT, single-excitation CI (CIS) and RPA. The module works with either closed-shell (RHF or RKS) or unrestricted (UHF or UKS) reference wavefunctions. For DFT models the module automatically chooses TD-DFT and for HF wavefunctions the CIS model. If the RI approximation is used in the SCF part it will also be used in the excited states calculation. A detailed documentation is provided in section Excited States via RPA, CIS, TD-DFT and SF-TDA
5.4.1.1. General Use¶
In its simplest form it is only necessary to provide the number of roots sought:
! BP86 def2-SVP TightSCF
%tddft
Nroots 10
triplets true
end
*xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
end
Which gives the following output:
------------------------------------
TD-DFT/TDA EXCITED STATES (SINGLETS)
------------------------------------
the weight of the individual excitations are printed if larger than 1.0e-02
STATE 1: E= 0.142238 au 3.870 eV 31217.5 cm**-1 <S**2> = 0.000000 Mult 1
7a -> 8a : 0.999852 (c= 0.99992610)
STATE 2: E= 0.279148 au 7.596 eV 61265.8 cm**-1 <S**2> = 0.000000 Mult 1
7a -> 9a : 0.991058 (c= 0.99551880)
STATE 3: E= 0.326547 au 8.886 eV 71668.9 cm**-1 <S**2> = 0.000000 Mult 1
5a -> 8a : 0.992394 (c= -0.99618994)
STATE 4: E= 0.339416 au 9.236 eV 74493.3 cm**-1 <S**2> = 0.000000 Mult 1
6a -> 8a : 0.214928 (c= 0.46360308)
7a -> 10a : 0.760130 (c= -0.87185424)
STATE 5: E= 0.357323 au 9.723 eV 78423.4 cm**-1 <S**2> = 0.000000 Mult 1
4a -> 8a : 0.998607 (c= 0.99930350)
STATE 6: E= 0.396031 au 10.777 eV 86918.7 cm**-1 <S**2> = 0.000000 Mult 1
7a -> 11a : 0.995757 (c= -0.99787607)
STATE 7: E= 0.412518 au 11.225 eV 90537.2 cm**-1 <S**2> = 0.000000 Mult 1
3a -> 8a : 0.015703 (c= 0.12531336)
6a -> 9a : 0.982525 (c= 0.99122380)
STATE 8: E= 0.420413 au 11.440 eV 92270.0 cm**-1 <S**2> = 0.000000 Mult 1
4a -> 10a : 0.023644 (c= -0.15376603)
5a -> 9a : 0.184687 (c= -0.42975192)
5a -> 11a : 0.029413 (c= -0.17150093)
6a -> 8a : 0.535798 (c= -0.73198239)
7a -> 10a : 0.161330 (c= -0.40165919)
7a -> 14a : 0.031134 (c= 0.17644805)
STATE 9: E= 0.454354 au 12.364 eV 99719.1 cm**-1 <S**2> = 0.000000 Mult 1
5a -> 9a : 0.801630 (c= 0.89533782)
5a -> 11a : 0.012558 (c= -0.11206253)
6a -> 8a : 0.103311 (c= -0.32142015)
7a -> 10a : 0.051303 (c= -0.22650208)
7a -> 14a : 0.016544 (c= 0.12862428)
STATE 10: E= 0.474384 au 12.909 eV 104115.2 cm**-1 <S**2> = 0.000000 Mult 1
6a -> 10a : 0.998860 (c= -0.99942977)
and the triplets:
------------------------------------
TD-DFT/TDA EXCITED STATES (TRIPLETS)
------------------------------------
the weight of the individual excitations are printed if larger than 1.0e-02
STATE 11: E= 0.114291 au 3.110 eV 25084.1 cm**-1 <S**2> = 2.000000 Mult 3
7a -> 8a : 0.999453 (c= 0.99972624)
STATE 12: E= 0.213324 au 5.805 eV 46819.1 cm**-1 <S**2> = 2.000000 Mult 3
6a -> 8a : 0.996522 (c= 0.99825941)
STATE 13: E= 0.255583 au 6.955 eV 56094.1 cm**-1 <S**2> = 2.000000 Mult 3
7a -> 9a : 0.992767 (c= 0.99637714)
STATE 14: E= 0.276345 au 7.520 eV 60650.8 cm**-1 <S**2> = 2.000000 Mult 3
5a -> 8a : 0.998251 (c= -0.99912505)
STATE 15: E= 0.316749 au 8.619 eV 69518.3 cm**-1 <S**2> = 2.000000 Mult 3
7a -> 10a : 0.991502 (c= -0.99574190)
STATE 16: E= 0.327793 au 8.920 eV 71942.2 cm**-1 <S**2> = 2.000000 Mult 3
4a -> 8a : 0.994029 (c= 0.99701018)
STATE 17: E= 0.377551 au 10.274 eV 82862.9 cm**-1 <S**2> = 2.000000 Mult 3
7a -> 11a : 0.998586 (c= -0.99929259)
STATE 18: E= 0.400159 au 10.889 eV 87824.7 cm**-1 <S**2> = 2.000000 Mult 3
3a -> 8a : 0.062364 (c= 0.24972706)
6a -> 9a : 0.934672 (c= -0.96678411)
STATE 19: E= 0.433339 au 11.792 eV 95107.0 cm**-1 <S**2> = 2.000000 Mult 3
5a -> 9a : 0.988277 (c= 0.99412115)
STATE 20: E= 0.445213 au 12.115 eV 97713.0 cm**-1 <S**2> = 2.000000 Mult 3
3a -> 8a : 0.934403 (c= 0.96664514)
6a -> 9a : 0.063400 (c= 0.25179341)
By default, it also prints the dipole absorption and circular dichroism spectra:
----------------------------------------------------------------------------------------------------
ABSORPTION SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS
----------------------------------------------------------------------------------------------------
Transition Energy Energy Wavelength fosc(D2) D2 DX DY DZ
(eV) (cm-1) (nm) (au**2) (au) (au) (au)
----------------------------------------------------------------------------------------------------
0-1A -> 1-3A 3.110029 25084.1 398.7 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 1-1A 3.870479 31217.5 320.3 0.000000000 0.00000 -0.00000 0.00000 0.00000
0-1A -> 2-3A 5.804830 46819.1 213.6 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 3-3A 6.954778 56094.1 178.3 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 4-3A 7.519743 60650.8 164.9 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 2-1A 7.595990 61265.8 163.2 0.139374365 0.74893 -0.00000 0.86541 -0.00000
0-1A -> 5-3A 8.619170 69518.3 143.8 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 3-1A 8.885804 71668.9 139.5 0.002010847 0.00924 0.00000 -0.00000 -0.09611
0-1A -> 6-3A 8.919695 71942.2 139.0 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 4-1A 9.235990 74493.3 134.2 0.021695302 0.09588 -0.30964 -0.00000 -0.00000
0-1A -> 5-1A 9.723256 78423.4 127.5 0.000000000 0.00000 -0.00000 0.00000 -0.00000
0-1A -> 7-3A 10.273692 82862.9 120.7 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 6-1A 10.776542 86918.7 115.1 0.009793664 0.03709 0.00000 -0.19260 -0.00000
0-1A -> 8-3A 10.888868 87824.7 113.9 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 7-1A 11.225180 90537.2 110.5 0.002033718 0.00740 0.00000 -0.00000 0.08599
0-1A -> 8-1A 11.440020 92270.0 108.4 0.371220034 1.32448 -1.15086 -0.00000 0.00000
0-1A -> 9-3A 11.791761 95107.0 105.1 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 10-3A 12.114872 97713.0 102.3 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 9-1A 12.363588 99719.1 100.3 0.259360077 0.85625 -0.92534 0.00000 0.00000
0-1A -> 10-1A 12.908634 104115.2 96.0 0.000000000 0.00000 -0.00000 -0.00000 -0.00000
------------------------------------------------------------------------------------------
CD SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS
------------------------------------------------------------------------------------------
Transition Energy Energy Wavelength R MX MY MZ
(eV) (cm-1) (nm) (1e40*cgs) (au) (au) (au)
------------------------------------------------------------------------------------------
0-1A -> 1-3A 3.110029 25084.1 398.7 -0.00000 0.00000 0.00000 0.00000
0-1A -> 1-1A 3.870479 31217.5 320.3 0.00000 0.58235 0.00000 0.00000
0-1A -> 2-3A 5.804830 46819.1 213.6 -0.00000 0.00000 0.00000 0.00000
0-1A -> 3-3A 6.954778 56094.1 178.3 -0.00000 0.00000 0.00000 0.00000
0-1A -> 4-3A 7.519743 60650.8 164.9 -0.00000 0.00000 0.00000 0.00000
0-1A -> 2-1A 7.595990 61265.8 163.2 -0.00000 -0.00000 0.00000 0.32961
0-1A -> 5-3A 8.619170 69518.3 143.8 -0.00000 0.00000 0.00000 0.00000
0-1A -> 3-1A 8.885804 71668.9 139.5 -0.00000 -0.00000 -0.73058 0.00000
0-1A -> 6-3A 8.919695 71942.2 139.0 -0.00000 0.00000 0.00000 0.00000
0-1A -> 4-1A 9.235990 74493.3 134.2 -0.00000 -0.00000 -0.00000 -0.00000
0-1A -> 5-1A 9.723256 78423.4 127.5 0.00000 0.31342 -0.00000 0.00000
0-1A -> 7-3A 10.273692 82862.9 120.7 -0.00000 0.00000 0.00000 0.00000
0-1A -> 6-1A 10.776542 86918.7 115.1 0.00000 0.00000 0.00000 0.58743
0-1A -> 8-3A 10.888868 87824.7 113.9 -0.00000 0.00000 0.00000 0.00000
0-1A -> 7-1A 11.225180 90537.2 110.5 -0.00000 0.00000 -0.06966 0.00000
0-1A -> 8-1A 11.440020 92270.0 108.4 -0.00000 -0.00000 -0.00000 0.00000
0-1A -> 9-3A 11.791761 95107.0 105.1 -0.00000 0.00000 0.00000 0.00000
0-1A -> 10-3A 12.114872 97713.0 102.3 -0.00000 0.00000 0.00000 0.00000
0-1A -> 9-1A 12.363588 99719.1 100.3 -0.00000 -0.00000 -0.00000 -0.00000
0-1A -> 10-1A 12.908634 104115.2 96.0 0.00000 0.00260 0.00000 0.00000
Which can be processed with orca_mapspc for plotting.
The triplets parameter is only valid for closed-shell references. If chosen as true the program will also determine the triplet excitation energies in addition to the singlets.
The collinear spin-flip version of CIS/TDA (always starting from an open-shell reference!) can be invoked in a similar manner, using:
%tddft
Nroots 5
sf true
end
Please check the section Collinear Spin-Flip TDA (SF-TD-DFT) for more details on how to use it, and how to understand its results.
If one wants to compute transient spectra, or transition dipoles
starting from a given excited state, the option DOTRANS must be set to
TRUE and an IROOT should be given for the initial state (the default is
1). If DOTRANS ALL is requested instead, the transition dipoles between
all states are computed. The transient transition dipoles will then be
printed after the normal spectra.
This option is currently only available for CIS/TDA and is done using the expectation value formalism, as the other transition dipole moments in ORCA.
%tddft
IROOT 2
DOTRANS TRUE
#or
DOTRANS ALL
end
5.4.1.2. Capabilities¶
Currently, the TD-DFT/CIS module is able to calculate excitation energies, absorption spectra and circular dichroism spectra. Within the TD-DFT method, magnetic circular dichroism (see Simulation of (Magnetic) Circular Dichroism and Absorption Spectra) and transient spectra can also be calculated.
Analytical gradients are available for TD-DFT in both restricted and unrestricted formalisms and also for the collinear spin-flip variant, which allows for geometry optimizations of excited states as described in Excited State Geometry Optimization.
5.4.2. Excited States with Restricted Open-shell CIS - ROCIS¶
In addition to the CIS/TD-DFT description of excited states, ORCA features the ROCIS method[587], [588], which performs configuration interaction with single excitations calculations using a restricted open-shell Hartree-Fock (ROHF) reference.
Starting from ORCA 6.0, the general-spin ROCIS (GS-ROCIS) [589] implementation is available.
This new implementation can handle CSFs with arbitrary spin couplings obtained via
the CSF-ROHF method as references.
The main scope of ROCIS is to calculate L-edge and M-edge X-ray absorption spectra (XAS) as well as X-ray
magnetic circular dichroism (XMCD) and resonant inelastic X-ray scattering (RIXS). The computational costs
are usually larger than TD-DFT, but significantly smaller than coupled-cluster based methods.
Together with the pair natural orbital approach (PNO-ROCIS), spectra of medium to large molecular sizes are feasible
to be calculated.
For a detailed documentation check Excited States via ROCIS and ROCIS/DFT.
5.4.2.1. General Use¶
The method is invoked by providing the number of roots sought in the
%rocis block of the input file:
!def2-SVP TightSCF
%scf
HFTyp ROHF
ROHF_CASE HIGHSPIN
ROHF_NEL[1] 2
end
%rocis
NRoots 10
end
* xyz 0 3
C 0 0 0.1058
H 0 0.9910 -0.3174
H 0 -0.9910 -0.3174
end
By default, the original ROCIS implementation is invoked, which is capable of dealing
only with high-spin ROHF references, giving the following output:
Eigenvectors of ROCIS calculation:
the threshold for printing is: 1e-02
i->a single excitation from orbital i to a
i->t->a single excitation from orbital i to a with a spin flip in orbital t
i->t ; w->a double excitation from orbital i to t and orbital w to a
STATE 0 Exc. Energy: 0.000mEh 0.000eV 0.0cm**-1
0 : 0.9880 (0.993993)
STATE 1 Exc. Energy: 291.825mEh 7.941eV 64048.2cm**-1
2->3 : 0.9602 (0.979900)
STATE 2 Exc. Energy: 307.258mEh 8.361eV 67435.4cm**-1
1->4 : 0.0244 (-0.156226)
4->5 : 0.9086 (-0.953183)
4->11 : 0.0379 (-0.194741)
1->3 ; 4->5 : 0.0126 (-0.112387)
STATE 3 Exc. Energy: 311.967mEh 8.489eV 68468.7cm**-1
2->4 : 0.9558 (-0.977660)
4->6 : 0.0181 (0.134462)
STATE 4 Exc. Energy: 349.147mEh 9.501eV 76629.0cm**-1
3->5 : 0.8588 (-0.926723)
3->11 : 0.0299 (-0.173056)
1->3 ->5 : 0.0561 (0.236925)
STATE 5 Exc. Energy: 374.241mEh 10.184eV 82136.4cm**-1
2->4 : 0.0187 (0.136885)
4->6 : 0.9224 (0.960395)
4->12 : 0.0360 (0.189800)
STATE 6 Exc. Energy: 413.285mEh 11.246eV 90705.6cm**-1
3->6 : 0.8368 (0.914777)
3->12 : 0.0307 (0.175082)
1->6 : 0.0148 (-0.121572)
1->3 ->6 : 0.0376 (-0.193912)
2->3 ->5 : 0.0456 (0.213492)
STATE 7 Exc. Energy: 474.514mEh 12.912eV 104143.8cm**-1
1->3 : 0.8308 (-0.911467)
2->3 ->6 : 0.0826 (0.287351)
2->3 ->12 : 0.0148 (0.121501)
STATE 8 Exc. Energy: 501.672mEh 13.651eV 110104.2cm**-1
1->4 : 0.8364 (-0.914550)
4->5 : 0.0249 (0.157804)
4->7 : 0.0561 (0.236863)
2->4 ; 3->6 : 0.0324 (-0.180124)
STATE 9 Exc. Energy: 511.571mEh 13.921eV 112276.9cm**-1
3->6 : 0.0580 (0.240898)
1->6 : 0.0166 (-0.128707)
2->5 : 0.1178 (0.343223)
2->3 ->5 : 0.3041 (-0.551423)
2->4 ->5 : 0.2625 (-0.512374)
The general-spin version GS-ROCIS can be requested via:
!def2-SVP TightSCF
%scf
HFTyp ROHF
ROHF_CASE HIGHSPIN
ROHF_NEL[1] 2
end
%rocis
DoGenROCIS true
ReferenceMult 3
NRoots 10
end
* xyz 0 3
C 0 0 0.1058
H 0 0.9910 -0.3174
H 0 -0.9910 -0.3174
end
The output gives the resulting spin coupling in addition to orbital information:
Eigenvectors of ROCIS calculation:
the threshold for printing is: 1e-02
i->a single excitation from orbital i to a
i->t ; w->a double excitation from orbital i to t and orbital w to a
STATE 0 Exc. Energy: 0.000mEh 0.000eV 0.0cm**-1
0 : 0.9880 (-0.993993) : spin coupling: 2+1+1 0
STATE 1 Exc. Energy: 291.825mEh 7.941eV 64048.2cm**-1
2->3 : 0.9602 (0.979900) : spin coupling: +1 2+1 0
STATE 2 Exc. Energy: 307.258mEh 8.361eV 67435.4cm**-1
1->4 : 0.0244 (-0.156226) : spin coupling: +1+1 2 0
4->5 : 0.9086 (-0.953183) : spin coupling: 2+1 0+1
4->11 : 0.0379 (-0.194741) : spin coupling: 2+1 0+1
1->3 ; 4->5 : 0.0126 (0.112387) : spin coupling: +1 2 0+1
STATE 3 Exc. Energy: 311.967mEh 8.489eV 68468.7cm**-1
2->4 : 0.9558 (0.977660) : spin coupling: +1+1 2 0
4->6 : 0.0181 (-0.134462) : spin coupling: 2+1 0+1
STATE 4 Exc. Energy: 349.147mEh 9.501eV 76629.0cm**-1
3->5 : 0.8588 (-0.926723) : spin coupling: 2 0+1+1
3->11 : 0.0299 (-0.173056) : spin coupling: 2 0+1+1
1->5 : 0.0695 (-0.263669) : spin coupling: +1-1+1+1
STATE 5 Exc. Energy: 374.241mEh 10.184eV 82136.4cm**-1
2->4 : 0.0187 (-0.136885) : spin coupling: +1+1 2 0
4->6 : 0.9224 (-0.960395) : spin coupling: 2+1 0+1
4->12 : 0.0360 (-0.189800) : spin coupling: 2+1 0+1
STATE 6 Exc. Energy: 413.285mEh 11.246eV 90705.6cm**-1
3->6 : 0.8368 (-0.914777) : spin coupling: 2 0+1+1
3->12 : 0.0307 (-0.175082) : spin coupling: 2 0+1+1
1->6 : 0.0609 (-0.246700) : spin coupling: +1-1+1+1
2->5 : 0.0242 (-0.155666) : spin coupling: +1+1+1-1
2->5 : 0.0345 (0.185684) : spin coupling: +1-1+1+1
STATE 7 Exc. Energy: 474.514mEh 12.912eV 104143.8cm**-1
1->3 : 0.8308 (-0.911467) : spin coupling: +1 2+1 0
2->6 : 0.0374 (0.193474) : spin coupling: +1+1+1-1
2->6 : 0.0631 (-0.251226) : spin coupling: +1-1+1+1
2->12 : 0.0134 (-0.115919) : spin coupling: +1-1+1+1
STATE 8 Exc. Energy: 501.672mEh 13.651eV 110104.2cm**-1
1->4 : 0.8364 (0.914550) : spin coupling: +1+1 2 0
4->5 : 0.0249 (-0.157804) : spin coupling: 2+1 0+1
4->7 : 0.0561 (-0.236863) : spin coupling: 2+1 0+1
2->4 ; 3->6 : 0.0324 (0.180124) : spin coupling: +1 0 2+1
STATE 9 Exc. Energy: 511.571mEh 13.921eV 112276.9cm**-1
3->6 : 0.0580 (0.240898) : spin coupling: 2 0+1+1
1->6 : 0.0311 (0.176432) : spin coupling: +1+1+1-1
2->5 : 0.6111 (-0.781719) : spin coupling: +1+1+1-1
2->5 : 0.0557 (0.235994) : spin coupling: +1+1-1+1
2->5 : 0.2060 (0.453844) : spin coupling: +1-1+1+1
2->11 : 0.0115 (0.107060) : spin coupling: +1-1+1+1
GS-ROCIS requires a valid ROHF solution as reference (either high-spin or a specific CSF).
For this, one would use the CSF-ROHF method to obtain the reference wavefunction for
which GS-ROCIS will be performed:
%scf
HFTyp ROHF
ROHF_CASE HIGHSPIN, USER_CSF or AF_CSF
end
For more details on the CSF-ROHF method, check ROHF Options.
The parametrized ROCIS/DFT formulation can be requested by:
%rocis
DoGenROCIS false # ROCIS/DFT is available only for the high-spin implementation of ROCIS.
DoDFTCIS true # Switches on the ROCIS/DFT method.
DFTCIS_c = 0.18, 0.20, 0.40 # Array input of the three parameters.
end
Important
Currently,
ROCIS/DFTis not implemented for the general-spin (GS-ROCIS) procedure.
5.4.2.2. Capabilities¶
At the present, ROCIS can be used to calculate excitation energies, absorption, circular dichroism and magnetic circular dichroism spectra. It is also capable of calculating resonant inelastic X-ray scattering (RIXS) spectra. Magnetic properties such as g-tensors, zero-field splittings, hyperfine couplings and electric field gradients are also available.
5.4.3. Excited States for Open-Shell Molecules with CASSCF Linear Response (MC-RPA)¶
ORCA has the possibility to calculate excitation energies, oscillator and rotatory strengths for CASSCF wave functions within the response theory (MC-RPA) formalism.[590, 591, 592] The main scope of MC-RPA is to simiulate UV/Vis and ECD absorption spectra of open-shell molecules like transition metal complexes and organic radicals. MC-RPA absorption spectra are usually more accurate than those obtained from the state-averaged CASSCF ansatz as orbital relaxation effects for excited states are taken into account. The computational costs are ususally larger than those of SA-CASSCF and should be comparable to a TD-DFT calculation for feasible active space sizes.
5.4.3.1. General Use¶
MC-RPA needs a converged state-specific CASSCF calculation of the electronic ground state. The only necessary information that the user has to provide is the desired number of excited states (roots). All other keywords are just needed to control the Davidson algorithm or post process the results. A minimal input for calculating the four lowest singlet excited states of ethylene could like the following:
#
# CASSCF + MCRPA for C2H4
#
! DEF2-SVP DEF2-TZVP/C VeryTightSCF
%casscf
nel 2
norb 2
mult 1
nroots 1
gtol 1e-6
etol 1e-10
end
%mcrpa
nroots 8
end
* int 0 1
C 0 0 0 0 0 0
C 1 0 0 1.3385 0 0
H 1 2 0 1.07 120 0
H 1 2 3 1.07 120 180
H 2 1 3 1.07 120 0
H 2 1 3 1.07 120 180
*
After the residual norm is below a user-given threshold TolR we get
the following information
--------------------------------------------------------------------------------------------
All 8 RPA Roots CONVERGED Below 1.000e-05
--------------------------------------------------------------------------------------------
3 (root 0) 3.352976e-01 3.489323e-07 Yes
(root 1) 3.485288e-01 1.656998e-08 Yes
(root 2) 3.514846e-01 2.178527e-08 Yes
(root 3) 3.741213e-01 2.577113e-07 Yes
(root 4) 3.743973e-01 2.416887e-08 Yes
(root 5) 4.040700e-01 4.609207e-08 Yes
(root 6) 4.479248e-01 1.240222e-08 Yes
(root 7) 4.609744e-01 6.311327e-09 Yes
and the absorption and ECD spectrum
----------------------------------------------------------------------------------------------------
ABSORPTION SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS
----------------------------------------------------------------------------------------------------
Transition Energy Energy Wavelength fosc(D2) D2 DX DY DZ
(eV) (cm-1) (nm) (au**2) (au) (au) (au)
----------------------------------------------------------------------------------------------------
0-1A -> 1-1A 9.123912 73589.3 135.9 0.430768702 1.92710 1.38820 -0.00000 -0.00000
0-1A -> 2-1A 9.483952 76493.2 130.7 0.009915132 0.04267 0.00000 -0.00000 -0.20657
0-1A -> 3-1A 9.564384 77142.0 129.6 0.000000000 0.00000 0.00000 0.00000 -0.00000
0-1A -> 4-1A 10.180358 82110.1 121.8 0.000000000 0.00000 -0.00000 -0.00000 -0.00000
0-1A -> 5-1A 10.187869 82170.7 121.7 0.000000000 0.00000 -0.00000 0.00000 0.00000
0-1A -> 6-1A 10.995304 88683.1 112.8 0.000000000 0.00000 0.00000 -0.00000 -0.00000
0-1A -> 7-1A 12.188654 98308.1 101.7 0.000000000 0.00000 -0.00000 -0.00000 -0.00000
0-1A -> 8-1A 12.543751 101172.2 98.8 0.000000000 0.00000 -0.00000 -0.00000 -0.00000
...
------------------------------------------------------------------------------------------
CD SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS
------------------------------------------------------------------------------------------
Transition Energy Energy Wavelength R MX MY MZ
(eV) (cm-1) (nm) (1e40*cgs) (au) (au) (au)
------------------------------------------------------------------------------------------
0-1A -> 1-1A 9.123912 73589.3 135.9 -0.00000 0.00000 0.00000 0.00000
0-1A -> 2-1A 9.483952 76493.2 130.7 -0.00000 -0.00000 0.00000 -0.00000
0-1A -> 3-1A 9.564384 77142.0 129.6 -0.00000 0.69943 0.00000 0.00000
0-1A -> 4-1A 10.180358 82110.1 121.8 -0.00000 -0.15776 0.00000 0.00000
0-1A -> 5-1A 10.187869 82170.7 121.7 -0.00000 0.00000 0.73302 -0.00000
0-1A -> 6-1A 10.995304 88683.1 112.8 0.00000 -0.00000 0.54037 0.00000
0-1A -> 7-1A 12.188654 98308.1 101.7 0.00000 -0.00000 0.00000 0.00000
0-1A -> 8-1A 12.543751 101172.2 98.8 -0.00000 -0.00000 0.00000 -0.90854
5.4.3.2. Capabilities¶
At the moment, we can simulate UV/Vis and ECD absorption spectra by
computing excitation energies, oscillator and rotatory strengths
(check section One Photon Spectroscopy for more information).
The code is parallelized and the computational bottleneck is the integral
direct AO-Fock matrix construction. All intermediates that depend on the
number of states are stored on disk, which makes the MC-RPA
implementation suitable for computing many low-lying electronic states
of larger molecules. Abelian point-group symmetry can be exploited in
the calculation (up to D\(_{\textrm{2h} }\)). But there are no
calculations of spin-flip excitations possible at the moment. That means
all excited states will have the same spin as the reference state, which
is specified in the %casscf input block.
It is also possible to analyze and visualize the ground-to-excited-state transitions by means of natural transition orbitals[593] (NTO), which is explained in more detail in section Excited States for Open-Shell Molecules with CASSCF Linear Response (MC-RPA).
For further details, please study our recent publications[592, 594].
5.4.4. Excited States with ADC2¶
Among the various approximate correlation methods available for excited states, one of the most popular one is algebraic diagrammatic construction(ADC) method. The ADC has it origin in the Green’s function theory. It expands the energy and wave-function in perturbation order and can directly calculate the excitation energy, ionization potential and electron affinity, similar to that in the EOM-CCSD method. Because of the symmetric eigenvalue problem in ADC, the calculation of properties are more straight forward to calculate than EOM-CCSD. In ORCA, only the second-order approximation to ADC(ADC2) is implemented. It scales as O(\(N^{5}\)) power of the basis set.
5.4.4.1. General Use¶
The simplest way to perform an ADC2 calculation is via the usage of the
ADC2 keyword, together with the specification of the desired number of
roots:
! ADC2 cc-pVDZ cc-pVDZ/C TightSCF
%mdci
nroots 9
end
*xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
*
The above input will call the ADC2 routine with default settings. The main output is a list of excitation energies, augmented with some further state specific data. The integral transformation in the ADC2 implementation of ORCA is done using the density-fitting approximation. Therefore, one need to specify an auxiliary basis. For the above input, the following output is obtained:
----------------------
ADC(2) RESULTS (RHS)
----------------------
IROOT= 1: 0.146914 au 3.998 eV 32243.8 cm**-1
Amplitude Excitation
-0.116970 4 -> 8
0.672069 7 -> 8
IROOT= 2: 0.286012 au 7.783 eV 62772.3 cm**-1
Amplitude Excitation
-0.659777 7 -> 9
IROOT= 3: 0.341919 au 9.304 eV 75042.5 cm**-1
Amplitude Excitation
-0.676913 5 -> 8
IROOT= 4: 0.352206 au 9.584 eV 77300.2 cm**-1
Amplitude Excitation
0.126824 4 -> 10
0.360690 6 -> 8
-0.547670 7 -> 10
IROOT= 5: 0.393965 au 10.720 eV 86465.3 cm**-1
Amplitude Excitation
0.551345 6 -> 8
0.363450 7 -> 10
-0.109270 6 -> 8 6 -> 8
IROOT= 6: 0.404946 au 11.019 eV 88875.4 cm**-1
Amplitude Excitation
0.669682 4 -> 8
0.126557 7 -> 8
IROOT= 7: 0.412800 au 11.233 eV 90599.2 cm**-1
Amplitude Excitation
-0.100274 4 -> 11
0.671884 7 -> 11
IROOT= 8: 0.439251 au 11.953 eV 96404.5 cm**-1
Amplitude Excitation
-0.674114 6 -> 9
0.104541 6 -> 9 6 -> 8
IROOT= 9: 0.486582 au 13.241 eV 106792.5 cm**-1
Amplitude Excitation
-0.654624 5 -> 9
The transition moment for ADC2 in ORCA is calculated using an EOM-like expectation value approach, unlike the traditionally used intermediate state representation. However, the two approaches gives almost identical result.
--------------------------------------------------------------------
SPECTRUM FOR LEFT-RIGHT TRANSITION MOMENTS
--------------------------------------------------------------------
----------------------------------------------------------------------------------------------------
ABSORPTION SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS
----------------------------------------------------------------------------------------------------
Transition Energy Energy Wavelength fosc(D2) D2 DX DY DZ
(eV) (cm-1) (nm) (au**2) (au) (au) (au)
----------------------------------------------------------------------------------------------------
0-1A -> 1-1A 3.997726 32243.8 310.1 0.000000000 0.00000 0.00000 0.00000 0.00000
0-1A -> 2-1A 7.782776 62772.3 159.3 0.096710371 0.50720 -0.00000 -0.70536 0.00000
0-1A -> 3-1A 9.304078 75042.5 133.3 0.002261744 0.00992 -0.00000 0.00000 -0.09835
0-1A -> 4-1A 9.584003 77300.2 129.4 0.007937829 0.03381 -0.18502 -0.00000 -0.00000
0-1A -> 5-1A 10.720332 86465.3 115.7 0.465055079 1.77067 1.32377 0.00000 -0.00000
0-1A -> 6-1A 11.019150 88875.4 112.5 0.000000000 0.00000 -0.00000 0.00000 -0.00000
0-1A -> 7-1A 11.232869 90599.2 110.4 0.022236623 0.08080 0.00000 -0.28105 -0.00000
0-1A -> 8-1A 11.952640 96404.5 103.7 0.009103120 0.03109 0.00000 -0.00000 0.17328
0-1A -> 9-1A 13.240575 106792.5 93.6 0.071433742 0.22021 -0.46692 -0.00000 0.00000
The IP and EA versions can be called using the keywords IP-ADC2 and EA-ADC2, respectively.
5.4.4.2. Capabilities¶
At present, the ADC2 module is able to perform excited, ionized and electron attached state calculations, only for closed-shell systems. No open-shell version of the ADC2 is currently available. Below are all the parameters that influence the ADC2 module.
%mdci
#ADC2 parameters - defaults displayed
NDav 20 # maximum size of reduced space (i.e. 20*NRoots)
CheckEachRoot true # check convergence for each root separately
RootHoming true # apply root homing
DoLanczos false # use the Lanczos procedure rather than Davidson
UseCISUpdate true # use diagonal CIS for updating
NInitS 0 # number of roots in the initial guess, if 0, use preset value
DoRootwise false # solves for each root separately,
# more stable for large number of roots
FOLLOWCIS false # follows the initial singles guess
end
One can notice that features available in the ADC2 module is quite limited as compared to the EOM module and the option to specifically target the core-orbitals are yet not available. A word of caution, The ‘second order black magic’ of ADC2 can fail in many of the cases. The readers are encouraged to try the DLPNO based EOM-CCSD methods(Excited States with DLPNO based coupled cluster methods) which are much more accurate and computationally efficient.
5.4.5. Excited States with STEOM-CCSD¶
The STEOM-CCSD method provides an efficient way to calculate excitation energies, with an accuracy comparable to the EOM-CCSD approach, at a nominal cost. A detailed description will be given in Section Excited States via STEOM-CCSD.
5.4.5.1. General Use¶
The simplest way to perform a STEOM calculation is using the
STEOM-CCSD keyword, together with the specification of the desired
number of roots (NRoots):
! STEOM-CCSD cc-pVDZ TightSCF
%mdci
NRoots 9 # Number of excited states
DoDbfilter true # Remove doubly excited states
end
*xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
*
The above input calls the STEOM routine with default settings, where,
for instance, the doubly excited states are eliminated
(DoDbFilter true). The main output is a list of excitation energies,
augmented with some further state specific data. The STEOMCC approach in
ORCA uses state-averaged CIS natural transition orbitals (NTO) for the
selection of the active space. For the above input, the following output
is obtained:
-------------------------------
STEOM-CCSD RESULTS (SINGLETS)
-------------------------------
IROOT= 1: 0.145378 au 3.956 eV 31906.7 cm**-1
Amplitude Excitation
-0.168322 4 -> 8
-0.984801 7 -> 8
Ground state amplitude: -0.000000
Percentage Active Character 99.91
Amplitude Excitation in Canonical Basis
-0.166144 4 -> 8
-0.975626 7 -> 8
0.123172 7 -> 13
IROOT= 2: 0.309944 au 8.434 eV 68024.9 cm**-1
Amplitude Excitation
-0.993139 7 -> 9
Ground state amplitude: 0.000000
Percentage Active Character 99.94
Amplitude Excitation in Canonical Basis
-0.989653 7 -> 9
IROOT= 3: 0.337588 au 9.186 eV 74092.0 cm**-1
Amplitude Excitation
-0.993709 5 -> 8
Ground state amplitude: -0.000002
Percentage Active Character 99.23
Amplitude Excitation in Canonical Basis
-0.984171 5 -> 8
0.136295 5 -> 13
IROOT= 4: 0.357393 au 9.725 eV 78438.7 cm**-1
Amplitude Excitation
-0.186839 4 -> 10
-0.755864 6 -> 8
-0.601549 7 -> 10
-0.112921 7 -> 12
Ground state amplitude: 0.026385
Percentage Active Character 99.71
Amplitude Excitation in Canonical Basis
-0.182608 4 -> 10
-0.752095 6 -> 8
-0.598472 7 -> 10
IROOT= 5: 0.386751 au 10.524 eV 84882.0 cm**-1
Amplitude Excitation
-0.980511 4 -> 8
0.178900 7 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.90
Amplitude Excitation in Canonical Basis
-0.971593 4 -> 8
0.121664 4 -> 13
0.179278 7 -> 8
IROOT= 6: 0.406225 au 11.054 eV 89156.2 cm**-1
Amplitude Excitation
0.532674 6 -> 8
-0.825021 7 -> 10
Ground state amplitude: -0.065794
Percentage Active Character 99.70
Amplitude Excitation in Canonical Basis
0.526200 6 -> 8
-0.817279 7 -> 10
IROOT= 7: 0.421236 au 11.462 eV 92450.6 cm**-1
Amplitude Excitation
-0.125749 4 -> 11
-0.985406 7 -> 11
Ground state amplitude: 0.000000
Percentage Active Character 99.85
Amplitude Excitation in Canonical Basis
0.124222 4 -> 11
0.983485 7 -> 11
IROOT= 8: 0.443588 au 12.071 eV 97356.3 cm**-1
Amplitude Excitation
0.106457 3 -> 8
0.992884 6 -> 9
Ground state amplitude: 0.000092
Percentage Active Character 99.78
Amplitude Excitation in Canonical Basis
0.106009 3 -> 8
0.987228 6 -> 9
IROOT= 9: 0.512311 au 13.941 eV 112439.3 cm**-1
Amplitude Excitation
-0.995561 6 -> 10
Ground state amplitude: -0.000001
Percentage Active Character 99.94
Amplitude Excitation in Canonical Basis
-0.985669 6 -> 10
0.157781 6 -> 15
The first set of excitation amplitudes, printed for each root, have been calculated in the CIS NTO (Natural Transition Orbitals) basis. The second set of amplitudes have been evaluated in the RHF canonical basis.
5.4.5.2. Capabilities¶
At present, the STEOM routine is able to calculate excitation energies,
for both closed- or open-shell systems, using an RHF or UHF reference
function, respectively. It can be used for both serial and parallel
calculations. The method is available in the back-tranformed PNO and
DLPNO framework allowing the calculation of large molecules (Section
Capabilities and
Excited States with DLPNO based coupled cluster methods). In the closed-shell case (RHF), a
lower scaling version can be invoked by setting the CCSD2 keyword to
true in the %mdci section, which sets a second order approximation to
the exact parent approach. The transition moments can also be obtained
for closed- and open-shell systems. For more details see Section
Excited States via STEOM-CCSD.
5.4.6. Excited States with IH-FSMR-CCSD¶
The intermediate Hamiltonian Fock-space coupled cluster method (IH-FSMR-CCSD) provides an alternate way to calculate excitation energies, with an accuracy comparable to the STEOM-CCSD approach. A detailed description is given in Section Excited States via IH-FSMR-CCSD.
5.4.6.1. General Use¶
The IH-FSMR-CCSD calculation is called using the simple input keyword
IH-FSMR-CCSD and specifying the desired number of excited states
(NRoots) in the %mdci block.:
! IH-FSMR-CCSD cc-pVDZ TightSCF
%mdci
nroots 6
end
*xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
*
The above input will call the IH-FSMR-CCSD routine with default settings. The main output is a list of excitation energies, augmented with some further state specific data. The IH-FSMR-CCSD approach in ORCA uses state-averaged CIS natural transition orbitals(NTO) for the selection of the active space - similar to STEOM-CCSD. For the above input, the following output is obtained:
-------------------------------
IH-FSMR-CCSD RESULTS (SINGLETS)
-------------------------------
IROOT= 1: 0.144808 au 3.940 eV 31781.8 cm**-1
Amplitude Excitation
-0.171178 4 -> 8
-0.984024 7 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.96
Amplitude Excitation in Canonical Basis
-0.169804 4 -> 8
-0.976596 7 -> 8
0.111105 7 -> 13
IROOT= 2: 0.309569 au 8.424 eV 67942.6 cm**-1
Amplitude Excitation
-0.994029 7 -> 9
Ground state amplitude: 0.000000
Percentage Active Character 99.79
Amplitude Excitation in Canonical Basis
-0.991036 7 -> 9
IROOT= 3: 0.337609 au 9.187 eV 74096.7 cm**-1
Amplitude Excitation
0.992246 5 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.29
Amplitude Excitation in Canonical Basis
0.985970 5 -> 8
-0.120519 5 -> 13
IROOT= 4: 0.354726 au 9.653 eV 77853.3 cm**-1
Amplitude Excitation
-0.167422 4 -> 10
0.125754 5 -> 11
-0.748485 6 -> 8
-0.575997 7 -> 10
-0.204999 7 -> 14
Ground state amplitude: 0.000000
Percentage Active Character 94.11
Warning:: the state may have not converged with respect to active space
-------------------- Handle with Care --------------------
Amplitude Excitation in Canonical Basis
-0.175024 4 -> 10
0.110821 5 -> 11
-0.745514 6 -> 8
-0.609903 7 -> 10
IROOT= 5: 0.386134 au 10.507 eV 84746.6 cm**-1
Amplitude Excitation
-0.980436 4 -> 8
0.180972 7 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.91
Amplitude Excitation in Canonical Basis
-0.972869 4 -> 8
0.111877 4 -> 13
0.180279 7 -> 8
IROOT= 6: 0.443256 au 12.062 eV 97283.4 cm**-1
Amplitude Excitation
-0.110780 3 -> 8
-0.991903 6 -> 9
Ground state amplitude: 0.000000
Percentage Active Character 99.71
Amplitude Excitation in Canonical Basis
-0.109728 3 -> 8
-0.988030 6 -> 9
The first set of excitation amplitudes, printed for each root, have been calculated in the CIS NTO (Natural Transition Orbitals) basis. The second set of amplitudes have been evaluated in the RHF canonical basis.
5.4.6.2. Capabilities¶
At present, the IH-FSMR-CCSD routine is able to calculate excitation energies, for only closed shell systems using an RHF reference. It can be used for both serial and parallel calculations. In the closed-shell case (RHF), a lower scaling version can be invoked by using bt-PNO approximation. The transition moments and solvation correction can be obtained using the CIS approximation.
5.4.7. Excited States with PNO based coupled cluster methods¶
The methods described in the previous section are performed over a canonical CCSD or MP2 ground state. The use of canonical CCSD amplitudes restricts the use of EOM-CC and STEOM-CC methods to small molecules. The use of MP2 amplitudes is possible (e.g. the EOM-CCSD(2) or STEOM-CCSD(2) approaches), but it seriously compromises the accuracy of the method.
The bt-PNO-EOM-CCSD methods gives an economical compromise between accuracy and computational cost by replacing the most expensive ground state CCSD calculation with a DLPNO based CCSD calculation. The typical deviation of the results from the canonical EOM-CCSD results is around 0.01 eV. A detailed description will be given in Excited States via PNO-based coupled cluster.
5.4.7.1. General Use¶
The simplest way to perform a PNO based EOM calculation is via the usage of the bt-PNO-EOM-CCSD keyword, together with the specification of the desired number of roots. The specification of an auxilary basis set is also required, just as for ground state DLPNO-CCSD calculations.
! bt-PNO-EOM-CCSD def2-TZVP def2-TZVP/C def2/J TightSCF
%mdci
nroots 9
end
*xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
*
The output is similar to that from a canonical EOM-CCSD calculation:
----------------------
EOM-CCSD RESULTS (RHS)
----------------------
IROOT= 1: 0.145420 au 3.957 eV 31915.9 cm**-1
Amplitude Excitation
0.650351 7 -> 8
-0.162540 7 -> 13
Ground state amplitude: 0.000000
Percentage singles character= 92.33
IROOT= 2: 0.311168 au 8.467 eV 68293.4 cm**-1
Amplitude Excitation
0.650800 7 -> 9
-0.155532 7 -> 11
Ground state amplitude: -0.000000
Percentage singles character= 90.95
IROOT= 3: 0.337404 au 9.181 eV 74051.7 cm**-1
Amplitude Excitation
0.652018 5 -> 8
-0.169980 5 -> 13
Ground state amplitude: 0.000000
Percentage singles character= 91.87
IROOT= 4: 0.348225 au 9.476 eV 76426.6 cm**-1
Amplitude Excitation
0.152132 7 -> 9
0.652819 7 -> 11
Ground state amplitude: 0.000000
Percentage singles character= 92.35
IROOT= 5: 0.354668 au 9.651 eV 77840.6 cm**-1
Amplitude Excitation
0.545649 6 -> 8
-0.339835 7 -> 10
0.170720 6 -> 8 6 -> 8
Ground state amplitude: 0.032711
Percentage singles character= 87.10
IROOT= 6: 0.379606 au 10.330 eV 83313.9 cm**-1
Amplitude Excitation
0.636153 4 -> 8
-0.160301 4 -> 13
-0.109552 7 -> 8
0.143497 7 -> 8 6 -> 8
Ground state amplitude: 0.000000
Percentage singles character= 88.55
IROOT= 7: 0.386807 au 10.526 eV 84894.3 cm**-1
Amplitude Excitation
0.257812 6 -> 8
0.584151 7 -> 10
0.181783 7 -> 14
Ground state amplitude: 0.038804
Percentage singles character= 90.30
IROOT= 8: 0.440552 au 11.988 eV 96690.1 cm**-1
Amplitude Excitation
-0.655574 6 -> 9
-0.104097 6 -> 16
-0.112700 6 -> 9 6 -> 8
Ground state amplitude: 0.000000
Percentage singles character= 87.92
IROOT= 9: 0.447219 au 12.169 eV 98153.2 cm**-1
Amplitude Excitation
0.162756 7 -> 8
0.651078 7 -> 13
Ground state amplitude: 0.000000
Percentage singles character= 90.36
The IP and EA versions can be called by using the keywords bt-PNO-IP-EOM-CCSD and bt-PNO-EA-EOM-CCSD, respectively. Furthermore, the STEOM version can be invoked by using the keywords bt-PNO-STEOM-CCSD.
5.4.7.2. Capabilities¶
All of the features of canonical EOM-CC and STEOM-CC are available in the PNO based approaches for both closed- and open-shell systems.
5.4.8. Excited States with DLPNO based coupled cluster methods¶
The DLPNO-STEOM-CCSD method uses the full potential of DLPNO to reduce the computational scaling while keeping the accuracy of STEOM-CCSD.
Important
DLPNO-STEOM-CCSD is currently only available for closed-shell systems!
5.4.8.1. General Use¶
The simplest way to perform a DLPNO based STEOM calculation is via the
usage of the STEOM-DLPNO-CCSD keyword, together with the specification
of the desired number of roots. The specification of an auxiliary basis
set is also required, just as for ground state DLPNO-CCSD calculations.
As any CCSD methods, it is important to allow ORCA to access a significant amount of memory. In terms of scaling the limiting factor of the method is the size of temporary files and thus the disk space. For molecules above 1500 basis functions it starts to increase exponentially up to several teraoctets.
Here is the standard input we would recommend for STEOM-DLPNO-CCSD calculations. More information on the different keywords and other capabilities are available in the detailed part of the manual Excited States via STEOM-CCSD, Excited States via DLPNO-STEOM-CCSD. The following publications referenced some applications for this method either in organic molecules [595], [596] or for Semiconductors [597].
! STEOM-DLPNO-CCSD def2-TZVP def2-TZVP/C def2/J TightSCF
%mdci
NRoots 6
DoRootWise true
OThresh 0.005
VThresh 0.005
TCutPNOSingles 1e-11
NDAV 400
DoStoreSTEOM true
DoSimpleDens false
AddL2Term True
DTol 1e-5
end
* xyz 0 1
C 0.016227 -0.000000 0.000000
O 1.236847 0.000000 -0.000000
H -0.576537 0.951580 -0.000000
H -0.576537 -0.951580 -0.000000
*
The output is similar to that from a canonical DLPNO-STEOM-CCSD calculation:
-------------------------------
STEOM-CCSD RESULTS (SINGLETS)
-------------------------------
IROOT= 1: 0.144275 au 3.926 eV 31664.7 cm**-1
Amplitude Excitation
-0.142146 4 -> 8
-0.988793 7 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.79
Amplitude Excitation in Canonical Basis
-0.134936 4 -> 8
-0.955031 7 -> 8
0.236743 7 -> 13
IROOT= 2: 0.308093 au 8.384 eV 67618.5 cm**-1
Amplitude Excitation
0.971471 7 -> 9
0.214898 7 -> 10
Ground state amplitude: -0.000000
Percentage Active Character 99.67
Amplitude Excitation in Canonical Basis
0.956929 7 -> 9
-0.236568 7 -> 11
0.102573 7 -> 16
IROOT= 3: 0.331790 au 9.028 eV 72819.4 cm**-1
Amplitude Excitation
0.993677 5 -> 8
Ground state amplitude: -0.000000
Percentage Active Character 98.87
Amplitude Excitation in Canonical Basis
0.957221 5 -> 8
-0.250140 5 -> 13
-0.105951 5 -> 18
IROOT= 4: 0.346876 au 9.439 eV 76130.4 cm**-1
Amplitude Excitation
-0.104901 4 -> 10
0.198176 7 -> 9
-0.972572 7 -> 10
Ground state amplitude: -0.000000
Percentage Active Character 99.65
Amplitude Excitation in Canonical Basis
0.100880 4 -> 11
0.218873 7 -> 9
0.956923 7 -> 11
-0.113897 7 -> 19
IROOT= 5: 0.347460 au 9.455 eV 76258.7 cm**-1
Amplitude Excitation
0.139551 4 -> 11
0.106649 4 -> 12
-0.801186 6 -> 8
0.455613 7 -> 11
0.302458 7 -> 12
Ground state amplitude: 0.027275
Percentage Active Character 87.08
Warning:: the state may have not converged with respect to active space
-------------------- Handle with Care --------------------
Amplitude Excitation in Canonical Basis
0.163791 4 -> 10
-0.785701 6 -> 8
0.159149 6 -> 13
0.527833 7 -> 10
-0.133085 7 -> 17
IROOT= 6: 0.379059 au 10.315 eV 83193.9 cm**-1
Amplitude Excitation
-0.983700 4 -> 8
0.155239 7 -> 8
Ground state amplitude: 0.000000
Percentage Active Character 99.48
Amplitude Excitation in Canonical Basis
-0.951092 4 -> 8
0.235046 4 -> 13
0.157714 7 -> 8
The IP and EA versions can be called by using the keywords IP-EOM-DLPNO-CCSD and EA-EOM-DLPNO-CCSD, respectively. As in canonical STEOM-CCSD, the first set of excitation amplitudes, printed for each root, are calculated in the CIS NTO (Natural Transition Orbitals) basis, while the second set is evaluated in the RHF canonical basis.