Post Hartree-Fock Methods in Q-Chem

For many types of systems, correlation is key. Whether you're determining the spin-orbit coupling of a strongly correlated transition metal complex, or simply need to add a bit of dynamical correlation to improve the accuracy of your results, Q-Chem has you covered. For handling dynamical correlation, we have a variety of perturbative approaches available, as well as coupled cluster and diagrammatic approaches. For those tricky systems where a single reference just won't do the job, consider one of our methods designed for handling strong correlation, such as CASSCF or selected CI.

Møller-Plesset Perturbation Theory

MP2RI-MP2SOS-MP2OO-MP2MP3MP4Dual-basis RI-MP2

Coupled-Cluster and Diagrammatic Theories

CCSDRI-CCSDCholesky-CCSDCCSD(T)EOM-CCSDADC

Methods for Strongly Correlated Systems

RAS-CIRAS-SFSF-TDDFTCASSCFNOCIv2RDMCCVB-SD


Q-Chem offers state-of-the-art tools for treating electron correlation effects, such as Møller-Plesset perturbation theory and coupled-cluster theory. For systems with strong correlation, Q-Chem offers specialty treatments including CASSCF, coupled-cluster valence bond theory, selected CI, RAS-CI, spin-flip, and variational 2-RDM methods.

MP2 Methods

  • RI-MP2 energy and gradients
  • Dual-Basis MP2
  • Optimized-Orbital MP2 improves accuracy for open-shell species
  • Latest κ-OOMP2 energies and gradients

Coupled-Cluster, Equation-of-Motion, and Algebraic Diagrammatic Construction Methods

  • Enhanced performance on multicore systems
  • RI and Cholesky decomposition
  • Optional single-precision execution within CC/EOM-CC for improved performance
  • Energy, gradient, and properties for CCSD, EOM-EE/SF/IP/EA-CCSD
  • Static and dynamic polarizabilities
  • Approximate EOM-CC methods for larger molecules
  • PCM and EFP embedding for ADC and EOM-CC wave functions
  • ADC and EOM methods for core-ionized and core-excited states

Methods for Strongly Correlated Systems

SMM modeled by SF-TDDFT