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1.3 Q-Chem Features

1.3.6 New Features in Q-Chem 5.0

(December 20, 2021)
  • Enhancements to the coupled-cluster package:

    • Analytic gradients for Cholesky-decomposed CCSD and EOM-CCSD; efficiency improvement for canonical CCSD and EOM-CCSD gradients (Xintian Feng, Evgeny Epifanovsky).

    • CAP-EOM-CCSD analytic gradients (Zsuzsanna Koczor-Benda, Thomas Jagau) and Dyson orbitals for metastable states (Thomas Jagau, Anna Krylov), Section 7.10.9).

    • CAP-EOM-MP2 method (Alexander Kunitsa, Ksenia Bravaya).

    • Evaluation of polarizabilities using CCSD and EOM-CCSD (EE and SF) wave functions using full derivative formulation (Kaushik Nanda and Anna Krylov), Section 7.10.21.4).

    • Evaluation of S2 for EOM-CCSD wave functions (X. Feng).

    • Evaluation of NACs for EOM-CCSD wave functions (Shirin Faraji, Anna Krylov, Evgeny Epifanovsky, Xintian Feng), Section 7.10.21.3).

    • Efficiency improvement and new multicore-parallel code for (T) correction (Ilya Kaliman).

    • New coupled-cluster based methods for core states (Anna Krylov).

  • New capabilities for implicit solvation modeling:

    • PCM capabilities for computing vertical excitation, ionization, and electron attachment energies at EOM-CC and MP2 levels (Section 7.10.16).

    • State-specific equilibrium and non-equilibrium solvation for all orders and variants of ADC (Jan Mewes, Andreas Dreuw) , Section 7.11.10.

    • Poisson equation boundary conditions allowing use of an arbitrary, anisotropic dielectric function ε(𝐫), with full treatment of volume polarization (Marc Coons, John Herbert), Section 11.2.11.

    • Composite Model for Implicit Representation of Solvent (CMIRS), an accurate model for free energies of solvation (Zhi-Qiang You, John Herbert), Section 11.2.7.

  • New density functionals (Narbe Mardirossian and Martin Head-Gordon), Section 5.3):

    • GGA functionals: BEEF-vdW, HLE16, KT1, KT2, KT3, rVV10

    • Meta-GGA functionals: B97M-rV, BLOC, mBEEF, oTPSS, TM

    • Hybrids: CAM-QTP(00), CAM-QTP(01), HSE-HJS, LC-ωPBE08, MN15, rCAM-B3LYP, WC04, WP04

    • Double hybrids: B2GP-PLYP, DSD-PBEB95-D3, DSD-PBEP86-D3, DSD-PBEPBE-D3, LS1DH-PBE, PBE-QIDH, PTPSS-D3, PWPB95-D3

    • Grimme’s PBEh-3c “low-cost” composite method

    • rVV10 non-local correlation functional

  • Additional DFT developments:

    • New forms of DFT-D3 (J. Witte; Section 5.7.3).

    • New standard integration grids, SG-2 and SG-3 (Saswata Dasgupta, John Herbert), Section 5.5.3.

    • More efficient propagator algorithms for time-dependent Kohn-Sham calculations, also known as “real-time” TDDFT (Ying Zhu, John Herbert), Section 7.4).

  • New integral package for for computing effective core potential (ECP) integrals (Simon McKenzie, Evgeny Epifanovsky), Chapter 8.9.1).

    • More efficient analytic algorithms for energies and first derivatives.

    • Support for arbitrary projector angular momentum.

    • Support up to h angular momentum in the basis set.

  • Analytic derivative couplings for the ab initio Frenkel-Davydov exciton model (Adrian Morrison, John Herbert); Section 12.17).

  • New ALMO-based energy decomposition analysis (EDA) methods:

    • The second-generation ALMO-EDA methods for DFT (Paul Horn, Yuezhi Mao, Martin Head-Gordon); Section 12.7.

    • The extension of ALMO-EDA to RIMP2 theory (Jonathan Thirman, Martin Head-Gordon); Section 12.8.

    • The “adiabatic" EDA method for decomposing changes in molecular properties (Yuezhi Mao, Paul Horn, MartinHead-Gordon); Section 12.10.

  • Wave function correlation capabilities:

    • Coupled cluster valence bond (CCVB) method for describing open-shell molecules with strong spin correlations (David Small, Martin Head-Gordon); Section 6.18.3.

    • Implementation of coupled-cluster valence bond with singles and doubles (CCVB-SD) for closed-shell species (Joonho Lee, David Small, Martin Head-Gordon); Section 6.12.4.

Note:  Several important changes in Q-Chem’s default settings have occurred since version 4.4. Core electrons are now frozen by default in most post-Hartree-Fock calculations; see Section 6.2. The keywords for calculation of SOCs and NACs were renamed for consistency between different methods. Some newer density functionals now use either the SG-2 or SG-3 quadrature grid by default, whereas all functionals used SG-1 by default in v. 4.4. Table 5.3 lists the default grid for various classes of functionals.