10.1. ORCA Structure

10.1.1. Program Components

The program system ORCA consists of several separate programs that call each other during a run. The following basic modules are included in this release (listed in alphabetical order):

orca	Main input+driver program
orca_ailft	Ab Initio Ligand Field Theory
orca_autoci	CI type program using the automated generation environment (ORCA-AGE)
orca_casscf	Main program for CASSCF driver
orca_casscfresp	CASSCF static linear response
orca_cclib	Precalculation of one particle coupling coefficients for ACCCI
orca_chelpg	Calculation of different kinds of ESP charges
orca_ciprep	Preparation of data for MRCI calculations (frozen core matrices and the like)
orca_cipsi	Iterative Configuration Expansion Configuration Interaction (ICE-CI)
orca_cis	Excited states via CIS and TD-DFT
orca_cisresp	CIS response calculation
orca_compound	General driver of the ORCA compound language
orca_crystalprep	Set up an embedding calculation from a crystal structure file
orca_eca	Auxiliary program for solving magnetic model Hamiltonians
orca_eda	Energy decomposition analysis module
orca_esd	Excited state dynamics program for calculating vibronic spectra, resonance Raman, …
orca_grad	General gradient module
orca_guess	Generation of an intial guess for SCF and CASSCF
orca_leanscf	Self consistent field program for HF and DFT
orca_lft	Ligand Field Theory
orca_loc	Calculation of localized molecular orbitals
orca_mcrpa	CASSCF linear response for excited states
orca_md	Molecular dynamics program
orca_mdci	Matrix driven correlation program: CI, CEPA, CPF, QCISD, CCSD(T)
orca_mm	Classical forcefield components
orca_mp2	MP2 program (conventional, direct and RI)
orca_mrci	MRCI and MRPT calculations (individually selecting)
orca_ndoint	Calculates semiempirical integrals and gradients
orca_nmrspectrum	Simulates NMR spectra from calculated NMR parameters
orca_numfreq	Numerical Hessian computation
orca_pc	Addition of point charge terms to the one-electron matrix
orca_plot	Generation of orbital and density plots
orca_pop	External program for population analysis on a given density
orca_prop	Calculation of molecular properties
orca_propint	Calculation of property integrals
orca_rel	(Quasi) Relativistic corrections
orca_rocis	Excited states via the ROCIS method
orca_scfgrad	Analytic derivatives of SCF energies (HF and DFT)
orca_scfresp	self consistent field response
orca_startup	Calculation of startup data before each single point
orca_vpot	Calculation of the electrostatic potential on a given molecular surface
orca_vpt2	VPT2 analysis