1.3.16 Summary of Features in Q-Chem Versions 3.$$x

DFT functionals and algorithms:

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

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

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

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

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

Solvation models:

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

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

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

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

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

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

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  SOS-CIS(D), SOS-CIS(D${}_0$), and RI-CIS(D) for excited states (D. Casanova, Y. M. Rhee, and M. Head-Gordon)

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  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):

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

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  Multi-threaded (OpenMP) parallel coupled-cluster calculations

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

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  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)

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

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

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  Two-layer ONIOM model (Y. Shao).

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

Improved two-electron integrals package

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

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  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:

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  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).

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  Available for RHF, UHF, and ROHF references.

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

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  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):

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  NMR chemical shifts

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  Static and dynamic polarizabilities

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

Anharmonic frequencies (C. Y. Lin)

Wave function analysis tools:

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

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

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

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

Graphical user interface (GUI) options:

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  IQmol, a fully integrated GUI. IQmol includes input file generator and contextual help, molecular builder, job submission tool, and visualization kit (molecular orbital and density viewer, frequencies, etc). For the latest version and download/installation instructions, please see the IQmol homepage (www.iqmol.org).

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  Seamless integration with the Spartan package (see www.wavefun.com).

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  Support for several other public-domain visualization programs:

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    WebMO
    https://www.webmo.net

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    Avogadro
    https://avogadro.cc

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    MolDen
    http://www.cmbi.ru.nl/molden

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    MacMolPlt (via a MolDen-formatted input file)
    https://brettbode.github.io/wxmacmolplt

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    JMol
    http://jmol.sourceforge.net/