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1.3 Q-Chem Features

1.3.4 New Features in Q-Chem 5.2

(February 4, 2022)
  • Changes in default settings:

    • Single-node shared-memory parallelism becomes default and recommended for most jobs. New command line key -mpi is required to use distributed-memory MPI-parallel features (Section 2.8).

    • Pure basis functions are used by default with BASIS = GEN.

    • Default number of grid points in Lebedev grids in solvent models changed from 302 to 194 points (non-Hydrogen) and 110 points (Hydrogen) atoms.

    • Use of SWIG charges for SMx models.

    • Input format for XPol, SAPT and XSAPT, and MBE jobs has changed.

    • Use EDA2 as the default driver for ALMO-EDA.

    • Frozen core approximation no longer applied by default in RAS-CI calculations.

  • General improvements:

    • Increased availability of basis sets: High angular momentum basis functions (up to k-functions) supported for most SCF, RI-MP2, CC, EOM-CC, ADC calculations.

    • Streamlined input format for RI-SCF calculations.

    • Added the def2- family of density fitted (RI) basis sets for SCF and post-SCF calculations (courtesy of Dr. Florian Weigend).

    • On-the-fly generation for the superposition of atomic densities guess for SCF (Kevin Carter-Fenk, John Herbert).

    • Reintroduction of legacy ECPs without fitting.

    • Easy specification of basis sets on fragments, reading of basis sets from an external file (Zheng Pei and Yihan Shao).

  • Improvements to the DFT capabilities:

    • Support for analytic frequency calculations using meta-GGA density functionals (available only with shared-memory parallelism).

    • Support for analytic frequency calculations using resolution-of-the-identity (density-fitted) Coulomb (available only with shared-memory parallelism).

    • Improved performance of analytic partial Hessian calculations using DFT.

    • New density functionals: revM06, revM11 (Pierpaolo Morgante and Roberto Peverati).

  • Improvements in implicit solvation models:

    • Revised PCM tessellation grids for improved performance (John Herbert).

    • Improved performance of the general SCF program with SMx solvation models (Yuezhi Mao).

  • New MP2 features:

    • Addition of regularized orbital-optimized second-order Møller-Plesset perturbation theory (κ-OOMP2) (Joonho Lee, Martin Head-Gordon; Section 6.6.6).

  • Enhancements to the coupled-cluster package:

    • Mixed-precision CCSD and EOM-CCSD (Pavel Pokhilko, Evvgeny Epifanovsky, Anna Krylov, with additional contributions from Ilya Kaliman, Kaushik Nanda, Marta Vidal, and Sonia Coriani; Sections 6.17 and 7.10.13).

    • Damped response, dynamic polarizabilities for two-electron absorption using EOM-CC (Kaushik Nanda and Anna Krylov).

    • Better handling of linear point groups in ADC and CC methods.

    • Improved performance of disk-based ADC/CC algorithms.

    • Projected and Voronoi CAP for CAP-EOM-CC/CC calculations (Ksenia Bravaya, Alexander Kunitsa; Section 7.10.9).

    • Dynamic polarizabilities for CCSD and EOM-CCSD (Kaushik Nanda, Anna Krylov; Section

    • Improved evaluation of spin-orbit coupling constants using EOM-CC wavefunctions (Pavel Pokhilko and Anna Krylov).

    • New features for SOC calculation and analysis (Pavel Pokhilko, Anna Krylov; Section

    • Dyson orbitals for CVS-EOM-CCSD (Marta Vidal, Sonia Coriani, Anna Krylov; Section 7.10.8).

  • Improvements in energy decomposition analysis methods:

    • Added electron density difference (EDD) plots and the ETS-NOCV analysis (Yuezhi Mao).

    • Added support for PCM and SMD solvation models in ALMO-EDA (Yuezhi Mao).

    • Resolved several issues that caused instabilities in MP2-EDA calculations (Yuezhi Mao).

  • New capabilities for explicit solvation modeling:

    • Polarizable Embedding (PE) Model for ground-state and ADC calculations (Maximilian Scheurer; Section 11.8).

  • Other new methods and capabilities:

    • Incremental FCI method (Paul Zimmerman).

    • Transition potential DFT for core-valence excitations.

    • Analytic evaluation of Raman intensities (Zheng Pei and Yihan Shao).