MOLCAS manual:

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5.1 Overview

MOLCAS contains a set of ab initio quantum chemical programs. These programs are essentially separate entities, but they are tied together by a shell. The exchange of information between the programs is through files. The shell is designed to allow ease of use with a minimum amount of specifications in a `run of the mill' case. The shell is flexible and allows the user to perform any calculation possible within the limitations of the various codes supplied with MOLCAS.

To make a calculation using MOLCAS you have to decide on which programs you need to use, prepare input for these, and construct a command procedure file to run the various programs. This command procedure file is submitted for batch execution. The following two subsections describe the programs available and the files used in MOLCAS.

5.1.1 Programs in the system

Below is a list of the available programs given. The programs are tied together with a shell and the inter-program information is passed through files. These files are also specified in this list to indicate the program module interdependencies.

ALASKAThis program computes the first derivatives of the one- and two-electron integrals with respect to the nuclear positions. The derivatives are not stored on files, but contracted immediately with the one- and two-electron densities to form the molecular gradients.
CASPT2This program computes the second order Many Body Perturbation Theory correction to CASSCF or RASSCF wave function.
CASVBThis program performs various types of valence bond calculations. It may be called directly (for VB interpretation of CASSCF wave functions), or within the RASSCF program (for fully variational VB calculations). In the former case it requires the information in the JOBIPH file generated by the RASSCF program, possibly also the integral files ONEINT and ORDINT.
CCSDTThis program performs the iterative ROHF CCSD procedure, optionally followed by the (T) calculation contribution. It requires the JOBIPH file produced by RASSCF, and TRAONE and TRAINT files produced by MOTRA.
CHCCThis program performs Closed-Shell Coupled-Clusters Singles and Doubles calculations based exclusively on the Cholesky (or RI) decomposed 2-electron integrals.
CMOCORRThis program compares the orbital spaces of two orbitals files.
CPFThis program produces a CPF, MCPF or ACPF wave function from a single reference configuration.
DYNAMIXThis program allows to do molecular dynamics simulations using the velocity Verlet algorithm. It has also the capability to detect non-adiabatic transition using a surface hopping algorithm.
ESPFThe ElectroStatic Potential Fitted (ESPF) method adds some one-electron operators to the one-electron hamiltonian in order to compute the interaction between the charge distribution and any kind of external electrostatic potential, field, and field derivatives.
EXPBASThis program takes one orbital file generated with a smaller basis set (ANO) and expands it to a larger basis set.
GATEWAYThis program collects all information about computed system, including geometry, basis sets and symmetry, and stores the data for a future use.

GENANOThis program is used to construct ANO type basis sets.

GRID_ITThis program calculates densities and molecular orbitals in a set of cartesian grid points, and produce a file for visualisation of MO's and densities.
FFPTThis program applies perturbations to the one-electron Hamiltonian for finite field perturbation calculations.
GUGAThis program generates the coupling coefficients required by the MRCI and CPF programs.
LOCALISATIONThis program generates localised occupied orbitals according to one of the following procedures: Pipek-Mezey, Boys, Edmiston-Ruedenberg, or Cholesky. Orthonormal, linearly independent, local virtual orbitals may also be generated from projected atomic orbitals (Cholesky PAOs).
LOPROPThis program computes molecular properties based on the one-electron density or transition-density and one-electron integrals like charges, dipole moments and polarizabilities
MBPT2This program computes the second order Many Body Perturbation Theory correction to an SCF wave function.
MCKINLEYThis program calculates the second and first order derivatives of integrals that are used for calculating second order derivatives of the energies with perturbation dependent basis sets.
MCLRThis program calculates the response of the wave function and related second order properties.
MOTRAThis program transforms one- and two-electron integrals from AO basis to MO basis. The integrals that are transformed are the one-electron Hamiltonian and the two-electron repulsion integrals.
MRCIThis program produces a Multi Reference CI wave function from an arbitrary set of reference configurations. Alternatively the program can produce an Averaged CPF wave function.
MULAThis program calculates intensities of vibrational transitions between electronic states.
NEMOA set of computational modules for calculation of interaction energies between molecules.
RASSCFThis program generates RASSCF type wave functions.
RASSIThis program computes the interaction between several RASSCF wave functions. A spin-orbit Hamiltonian can be used.
SCFThis program generates Closed Shell SCF or Unrestricted SCF, and Kohn-Sham DFT wave functions.
SEWARDThis program generates one- and two-electron integrals needed by other programs. If requested the two-electron integrals are computed in the form of Cholesky decomposed vectors.
SINGLE_ANISOThis program allows the non-perturbative calculation of effective spin (pseudospin) Hamiltonians and static magnetic properties of mononuclear complexes and fragments completely ab initio, including the spin-orbit interaction.
SLAPAFThis program is a general purpose facility for geometry optimization, transition state search, MEP, conical intersections, intersystem crossings, etc. using analytical or numerical gradients produced by ALASKA.
VIBROTThis program computes the vibrational-rotational spectrum of a diatomic molecule. Spectroscopic constants are computed. The program can also compute transition moments, life times , etc for excited state potentials.

5.1.2 Files in the system

The following is a list of the most common files in MOLCAS that are used to exchange information between program modules. The names given in this list are the FORTRAN file names, defined in the source code. Actual file names are constructed from so called prgm tables, specific for each individual module. (More information about PRGM files can be found in the Molcas Programming Guide).

RUNFILEThis file contains general information of the calculation. All programs read from it and write to it. GATEWAY creates a new RUNFILE corresponding to a new calculation.
ONEINTThis file contains the one-electron integrals generated by the program SEWARD.
ORDINTThis file contains the ordered two-electron integrals generated by the program SEWARD.
RYSRWData base for the fast direct evaluation of roots and weights of the Rys polynomials. This file is a part of the program system and should not be manipulated by the user.
ABDATAData base for the evaluation of roots and weights of high order Rys polynomial. This file is a part of the program system and should not be manipulated by the user.
CHVECThis file contains the Cholesky vectors representing the two-electron integrals as generated by the program SEWARD.
CHORSTThis file contains information about each of the Cholesky vectors generated by the program SEWARD.
CHREDThis file contains information about the storage mode of the Cholesky vectors generated by the program SEWARD.
CHOR2FFile containing the mapping between Cholesky vector storage and the canonical orbital ordering.
TRAINTThis file contains the transformed two-electron integrals generated by the program MOTRA.
TRAONEThis file contains the transformed one-electron integrals generated by the program MOTRA.
INPORBA generic name for an orbital file. Different programs uses and/or generates INPORB files with a specific name:
generated by the program GUESSORB.
generated by the program SCF.
generated by the program RASSCF.
generated by the program MRCI
generated by the program CPF.
generated by the program RASSI.
generated by the program CASPT2.
JOBIPHThis file contains the RASSCF wave function information generated by the RASSCF program.
JOBOLDThis file contains the RASSCF wave function information generated by the RASSCF program in the file JOBIPH, and is used as input for a subsequent RASSCF calculation.
JOBMIXThis file contains the multi-state CASPT2 wave function information generated by the CASPT2 program, and is used as input for a subsequent RASSI calculation.
GRIDThis file contains binary or ASCII data generated by GRID_IT program for visualization of density or molecular orbitals.

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Next: 5.2 Commands and environment Up: 5. The MOLCAS environment Previous: 5. The MOLCAS environment