1.3 Q-Chem Features

1.3.12 Summary of Features in Q-Chem versions 3.x

(May 16, 2021)
  • DFT functionals and algorithms:

    • Long-ranged corrected (LRC) functionals, also known as range-separated hybrid functionals (M. A. Rohrdanz and J. M. Herbert)

    • Constrained DFT (Q. Wu and T. Van Voorhis)

    • Grimme’s “DFT-D” empirical dispersion corrections (C.-D. Sherrill)

    • “Incremental” DFT method that significantly accelerates exchange-correlation quadrature in later SCF cycles (S. T. Brown)

    • Efficient SG-0 quadrature grid with approximately half the number of grid points relative to SG-1 (S.-H. Chien)

  • Solvation models:

    • SM8 model (A. V. Marenich, R. M. Olson, C. P. Kelly, C. J. Cramer, and D. G. Truhlar)

    • Onsager reaction-field model (C.-L. Cheng, T. Van Voorhis, K. Thanthiriwatte, and S. R. Gwaltney)

    • Chipman’s SS(V)PE model (S. T. Brown)

  • Second-order perturbation theory algorithms for ground and excited states:

    • Dual-basis RIMP2 energy and analytical gradient (R. P. Steele, R. A. DiStasio Jr., and M. Head-Gordon)

    • O2 energy and gradient (R. C. Lochan and M. Head-Gordon)

    • SOS-CIS(D), SOS-CIS(D0), and RI-CIS(D) for excited states (D. Casanova, Y. M. Rhee, and M. Head-Gordon)

    • Efficient resolution-of-identity (RI) implementations of MP2 and SOS-MP2 (including both energies and gradients), and of RI-TRIM and RI-CIS(D) energies (Y. Jung, R. A. DiStasio, Jr., R. C. Lochan, and Y. M. Rhee)

  • Coupled-cluster methods (P. A. Pieniazek, E. Epifanovsky, A. I. Krylov):

    • IP-CISD and EOM-IP-CCSD energy and gradient

    • Multi-threaded (OpenMP) parallel coupled-cluster calculations

    • Potential energy surface crossing minimization with CCSD and EOM-CCSD methods (E. Epifanovsky)

    • Dyson orbitals for ionization from the ground and excited states within CCSD and EOM-CCSD methods (M. Oana)

  • QM/MM methods (H. L. Woodcock, A. Ghysels, Y. Shao, J. Kong, and H. B. Brooks)

    • Q-Chem/Charmm interface (H. L. Woodcock)

    • Full QM/MM Hessian evaluation and approximate mobile-block-Hessian evaluation

    • Two-layer ONIOM model (Y. Shao).

    • Integration with the Molaris simulation package (E. Rosta).

  • Improved two-electron integrals package

    • Rewrite of the Head-Gordon–Pople algorithm for modern computer architectures (Y. Shao)

    • Fourier Transform Coulomb method for linear-scaling construction of the Coulomb matrix, even for basis sets with high angular moment and diffuse functions (L. Fusti-Molnar)

  • Dual basis self-consistent field calculations, offering an order-of-magnitude reduction in the cost of large-basis DFT calculations (J. Kong and R. P. Steele)

  • Enhancements to the correlation package including:

    • Most extensive range of EOM-CCSD methods available including EOM-SF-CCSD, EOM-EE-CCSD, EOM-DIP-CCSD, EOM-IP/EA-CCSD (A. I. Krylov).

    • Available for RHF, UHF, and ROHF references.

    • Analytic gradients and properties calculations (permanent and transition dipoles etc..).

    • Full use of Abelian point-group symmetry.

  • Coupled-cluster perfect-paring methods applicable to systems with >100 active electrons (M. Head-Gordon)

  • Transition structure search using the “growing string” algorithm (A. Heyden and B. Peters):

  • Ab initio molecular dynamics (J. M. Herbert)

  • Linear scaling properties for large systems (J. Kussmann, C. Ochsenfeld):

    • NMR chemical shifts

    • Static and dynamic polarizabilities

    • Static hyper-polarizabilities, optical rectification, and electro-optical Pockels effect

  • Anharmonic frequencies (C. Y. Lin)

  • Wave function analysis tools:

    • Analysis of intermolecular interactions with ALMO-EDA (R. Z. Khaliullin and M. Head-Gordon)

    • Electron transfer analysis (Z.-Q. You and C.-P. Hsu)

    • Spin densities at the nuclei (V. A. Rassolov)

    • Position, momentum, and Wigner intracules (N. A. Besley and D. P. O’Neill)

  • Graphical user interface (GUI) options: