Enhancements to the coupled-cluster package:
Analytic gradients for Cholesky-decomposed CCSD and EOM-CCSD; efficiency improvement for canonical CCSD and EOM-CCSD gradients (X. Feng, E. Epifanovsky).
CAP-EOM-CCSD analytic gradients (Z. Benda and T.-C. Jagau) and Dyson orbitals for metastable states (T.-C. Jagau, A.I. Krylov), Section 7.10.7).
CAP-EOM-MP2 method (A. Kunitsa, K. Bravaya).
Evaluation of polarizabilities using CCSD and EOM-CCSD (EE and SF) wave functions using full derivative formulation (K. Nanda and A. Krylov, Section 220.127.116.11).
Evaluation of for EOM-CCSD wave functions (X. Feng).
Evaluation of NACs for EOM-CCSD wave functions (S. Faraji, A. Krylov, E. Epifanovski, X. Feng, Section 18.104.22.168).
Efficiency improvement and new multicore-parallel code for (T) correction (I. Kaliman).
New coupled-cluster based methods for core states (A. 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 7.10.13).
State-specific equilibrium and non-equilibrium solvation for all orders and variants of ADC (J. M. Mewes and A. Dreuw; Section 7.11.7).
Poisson equation boundary conditions allowing use of an arbitrary, anisotropic dielectric function , with full treatment of volume polarization (M. P. Coons and J. M. Herbert; Section 11.2.10).
Composite Model for Implicit Representation of Solvent (CMIRS), an accurate model for free energies of solvation (Section 11.2.6)
New density functionals (N. Mardirossian and M. 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-PBE08, 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
New integral package for for computing effective core potential (ECP) integrals (S. C. McKenzie, E. Epifanovsky; Chapter 8.9).
More efficient analytic algorithms for energies and first derivatives.
Support for arbitrary projector angular momentum.
Support up to angular momentum in the basis set.
Analytic derivative couplings for the ab initio Frenkel-Davydov exciton model (A. F. Morrison and J. M. Herbert; Section 12.17).
New ALMO-based energy decomposition analysis (EDA) methods:
The second-generation ALMO-EDA methods for DFT (P. R. Horn, Y. Mao and M. Head-Gordon; Section 12.7)
The extension of ALMO-EDA to RIMP2 theory (J. Thirman and M. Head-Gordon; Section 12.8)
The “adiabatic" EDA method for decomposing changes in molecular properties (Y. Mao, P. R. Horn and M. Head-Gordon; Section 12.10)
Wave function correlation capabilities:
Coupled cluster valence bond (CCVB) method for describing open-shell molecules with strong spin correlations (D. W. Small and M. Head-Gordon; Section 6.16.2).
Implementation of coupled-cluster valence bond with singles and doubles (CCVB-SD) for closed-shell species (Joonho Lee, D. W. Small and M. Head-Gordon; Section 6.10.4).
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.