1.3 Q-Chem Features

1.3.2 New Features in Q-Chem 5.1

  • Improved OpenMP parallelization for:

    • SCF vibrational frequency calculations (Z. Gan)

    • RIMP2 gradient (F. Rob, Joonho Lee, X. Feng, & E. Epifanovsky)

  • Complete active space self-consistent field (CASSCF) and adaptive sampling CI (D. Levine, M. Head-Gordon)

  • Tkatchenko-Scheffler van der Waals method (Section 5.7.4) and many-body dispersion method (Section 5.7.5) (D. Barton, Ka Un Lao, & R. DiStasio)

  • Enhancements to the coupled-cluster package:

    • Core/valence separation for EOM-CCSD core-level excited and ionized states (M. Vidal, A.I. Krylov, X. Feng, E. Epifanovsky & S. Coriani), Section 7.8.5.

    • NTO analysis of two-photon transitions (K. Nanda & A.I. Krylov), Section 7.8.16.1.

    • NTO analysis of the complex-valued EOM wave functions (A.I. Krylov, W. Skomorowski), Section 7.8.16.

    • Analytic gradients for Cholesky-decomposed and resolution-of-identity CCSD and EOM-CCSD (X. Feng, A.I. Krylov).

    • Improved performance, reduced disk usage by coupled-cluster methods (E. Epifanovsky, I. Kaliman, & X. Feng).

  • New features in NTO analysis: Energies of NTOs (A.I. Krylov), Section 11.2.6.

  • Finite-difference evaluation of non-linear properties (M. de Wergifosse & A.I. Krylov), Section 11.14.2.

  • Poisson boundary conditions for SCF calculations (M. Coons & J. Herbert), Section 12.2.10.

    • 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 13.14 (Ka Un Lao, K. Fenk, & J. Herbert)

    • ALMO-EDA for CIS and TDDFT/TDA excited states, Section 13.10 (Qinghui Ge, Yuezhi Mao, & M. Head-Gordon)

    • Perturbative ALMO-CTA and COVP analysis in EDA2 (Yuezhi Mao & M. Head-Gordon)

  • Analytic derivative couplings for computing excitation/vibration energy couplings within the ab initio Frenkel-Davydov exciton model (A. Morrison & J. Herbert), Section 13.16.

  • Hyperfine spin-spin couplings and nuclear electric quadrupole couplings, Section 11.13.3 (E. Berquist & D. Lambrecht)

  • Variational two-electron reduced-density-matrix (v2RDM) and v2RDM-driven complete active space self-consistent field (v2RDM-CASSCF) method (G. Gidofalvi, L. Koulias, J.W. Mullinax, & A.E. DePrince III)

  • Frozen and restrained potential energy scans, Section 10.4 (Yihan Shao)

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