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1.3 Q-Chem Features

1.3.5 New Features in Q-Chem 5.1

(December 20, 2021)
  • Improved OpenMP parallelization for:

    • SCF vibrational frequency calculations (Zhengting Gan)

    • RIMP2 gradient (Fazle Rob, Joonho Lee, Xintian Feng, Evgeny Epifanovsky)

  • Complete active space self-consistent field (CASSCF) and adaptive sampling CI (Daniel Levine, Martin Head-Gordon)

  • Tkatchenko-Scheffler van der Waals method (Section 5.7.5) and many-body dispersion method (Section 5.7.6) (Denis Barton, Ka Un Lao, & Rob DiStasio)

  • Enhancements to the coupled-cluster package:

    • Core/valence separation for EOM-CCSD core-level excited and ionized states (Marta Vidal, Anna Krylov, Xintian Feng, Evgeny Epifanovsky, Sonia Coriani), Section 7.10.8.

    • NTO analysis of two-photon transitions (Kaushik Nanda, Anna Krylov), Section 7.10.21.1.

    • NTO analysis of the complex-valued EOM wave functions (Anna Krylov, Wojciech Skomorowski), Section 7.10.21.

    • Analytic gradients for Cholesky-decomposed and resolution-of-identity CCSD and EOM-CCSD (Xintian Feng, Anna Krylov).

    • Improved performance, reduced disk usage by coupled-cluster methods (Evgeny Epifanovsky, Ilya Kaliman, Xintian Feng).

  • New features in NTO analysis: Energies of NTOs (Anna Krylov), Section 10.2.9.

  • Finite-difference evaluation of non-linear properties (Marc de Wergifosse, Anna Krylov), Section 10.12.3.

  • Poisson boundary conditions for SCF calculations (Marc Coons, John Herbert), Section 11.2.11.

    • Enables quantum chemistry calculations in an arbitrary (anisotropic and inhomogeneous) dielectric environment.

    • Nonequilibrium solvent corrections for vertical ionization energies.

  • Energy decomposition analysis (EDA):

    • EDA based on symmetry-adapted perturbation theory and constrained DFT (SAPT/cDFT-EDA), Section 12.15 (Ka Un Lao, Kevin Carter-Fenk, John Herbert)

    • ALMO-EDA for CIS and TDDFT/TDA excited states, Section 12.11 (Qinghui Ge, Yuezhi Mao, Martin Head-Gordon)

    • Perturbative ALMO-CTA and COVP analysis in EDA2 (Yuezhi Mao, Martin Head-Gordon)

  • Analytic derivative couplings for computing excitation/vibration energy couplings within the ab initio Frenkel-Davydov exciton model (Adrian Morrison, John Herbert), Section 12.17.

  • Hyperfine spin-spin couplings and nuclear electric quadrupole couplings, Section 10.11.4 (Eric Berquist, Daniel Lambrecht)

  • Variational two-electron reduced-density-matrix (v2RDM) and v2RDM-driven complete active space self-consistent field (v2RDM-CASSCF) method (Gergely Gidofalvi, Lauren Koulias, Wayne Mullinax, Eugene DePrince)

  • Frozen and restrained potential energy scans, Section 9.6 (Yihan Shao)

  • Extended ESP charge fitting procedure to the computation of RESP charges (Yihan Shao)