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Molcas logo300.jpg
Developer(s)Lund University, Uppsala University, etc.
Stable release
8.0 / June 2014
Operating systemLinux, Unix and Unix-like operating systems, Microsoft Windows, Mac OS X
TypeComputational Chemistry
LicenseProprietary, LGPL 2.1,

MOLCAS is an ab initio computational chemistry program, developed as a joint project by a number of international institutes. Focus in the program is placed on methods for calculating general electronic structures in molecular systems in both ground and excited states.

In September 2017 the bulk of the MOLCAS code was released as open source (LGPL 2.1 license), under the name OpenMolcas[1].


  • Ab initio Hartree–Fock (HF), Density functional theory (DFT), second order Møller–Plesset perturbation theory, MCSCF, MRCI, CC, ((X)MS-)CASPT2 wavefunctions and energies[2]
  • Analytic gradient geometry optimization based on HF, DFT, CASSCF, and RASSCF wavefunctions
  • Cholesky decomposition (CD) and Resolution of the identity (RI) techniques for HF, DFT, CASSCF, CC, MBPT2, and CASPT2.
  • Analytical gradients and non-adiabatic coupling vectors.
  • On-the-fly auxiliary basis function technique, aCD and acCD.
  • CD/RI gradients for DFT functionals.
  • Numerical gradient geometry optimization based on CASPT2 wavefunctions.
  • Excited state energies for all wavefunctions, and excited optimized geometries from state averaged CASSCF wavefunctions.
  • Transition properties in excited states calculated at the CASSCF/RASSCF level, using a unique RASSCF State Interaction Method.
  • Solvent effects can be treated by the Onsager spherical cavity model or Polarizable continuum model (PCM).
  • Combined QM and molecular mechanics calculations for systems such as proteins and molecular clusters.
  • The NEMO procedure for creating intermolecular force fields for MC/MD simulations; these force fields include electrostatics, induction, dispersion, and exchange-repulsion terms and are based on calculations for individual molecules.
  • Graphical selection of the active space
  • Tully Surface Hopping Molecular Dynamics
  • Method for localization and characterization of conical intersections and seams


  1. ^
  2. ^ Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table, doi:10.1002/jcc.24221

External links[edit]