1.6 Q-Chem Features
Quantum chemistry methods have proven invaluable for studying chemical and physical properties of molecules. The Q-Chem system brings together a variety of advanced computational methods and tools in an integrated ab initio software package, greatly improving the speed and accuracy of calculations being performed. In addition, Q-Chem will accommodate far large molecular structures than previously possible and with no loss in accuracy, thereby bringing the power of quantum chemistry to critical research projects for which this tool was previously unavailable. Below is a reverse-chronological listing of new features added to various versions of Q-Chem.
1.6.1 New Features in Q-Chem 4.3
Q-Chem 4.3 provides several bug fixes, performance enhancements, and the following new features:
Analytic derivative couplings (i.e., nonadiabatic couplings) between electronic states computed at the CIS, spin-flip CIS, TDDFT, and spin-flip TDDFT levels (S. Fatehi, Q. Ou, J. E. Subotnik, X. Zhang, J. M. Herbert; Section 10.3).
A third-generation (“+D3”) dispersion potential for XSAPT (K. U. Lao, J. M. Herbert; Section 12.9).
Non-equilibrium PCM for computing vertical excitation energies (at the TDDFT level) and ionization potentials in solution (Z.-Q. You and J. M. Herbert; Section 11.2.2.3).
Spin-orbit couplings between electronic states for CC and EOM-CC wave functions (E. Epifanovsky, J. Gauss, A. I. Krylov; Section 6.7.12.2).
The PARI-K method for evaluation of exact exchange yields dramatic speedups for TZ and greater basis set hybrid DFT calculations (S. Manzer, M. Head-Gordon).
Transition moments and cross sections for two-photon absorption using EOM-CC wave functions (K. Nanda, A. I. Krylov; Section 6.7.12.1).
New excited-state analysis for ADC and CC/EOM-CC methods (M. Wormit; Section 10.2.7).
New Dyson orbital code for EOM-IP-CCSD and EOM-EA-CCSD (A. Gunina, A. I. Krylov; Section 6.7.23).
TAO-DFT: Thermally-assisted-occupation density functional theory (J.-D. Chai; Section 4.3.12).
MP2[V], a dual basis method that approximates the MP2 energy (J. Deng, A. Gilbert).
Iterative Hirshfeld population analysis for charges systems, and CM5 semi-empirical charge scheme (K. U. Lao, J. M. Herbert; Section 10.2.1).
New DFT Functionals
Long-range corrected functionals with empirical dispersion-correction schemes:
M05-D, B97X-D3 and M06-D3 (Y.-S. Lin, K. Hui, J.-D. Chai; Section 4.3.4.4). PBE0_DH and PBE0_2 double-hybrid functionals (K. Hui, J.-D. Chai; Section 4.3.9).
AK13 (K. Hui, J.-D. Chai).
LFAs asymptotic correction scheme (P.-T. Fang, J.-D. Chai).
HOMO-LUMO gap output, LDA/GGA fundamental gap using frozen-orbital approximation (K. Hui, J.-D. Chai; Section 4.3.11).
1.6.2 New Features in Q-Chem 4.2
New features, enhancements, and bug fixes in Q-Chem 4.2 are as follows.
Input file changes
New keyword METHOD simplifies input in most cases by replacing the pair of keywords EXCHANGE and CORRELATION (see Section 3.8).
Keywords for requesting excited state calculations have changed. Consult Chapter 6 for more details.
Keywords for solvation models have changed. Consult Section 11.2 for details.
New features for NMR calculations including spin-spin couplings (J. Kussmann, A. Luenser, C. Ochsenfeld; Section 10.16).
New built-in basis sets (Chapter 7).
New features and performance improvements in EOM-CC:
EOM-CC methods extended to treat metastable electronic states (resonances) via complex-scaling and complex absorbing potential approaches (D. Zuev, T.-C. Jagau, Y. Shao, A. I. Krylov; Section 6.7.5).
New features are added to EOM-CC iterative solvers, such as methods for interior eigenvalues and user-specified guesses (D. Zuev; Section 6.7.8).
Multicore parallel code for EOM-CC/CC gradients; improved (T) performance.
New features and performance improvements in ADC methods (M. Wormit, A. Dreuw):
SM12 implicit solvation model (A. V. Marenich, D. G. Truhlar, Y. Shao; Section 11.2.7.1).
NBO v. 6 interface (Section 10.4).
MECP optimization is now available with SOS-CIS(D) and TD-DFT (X. Zhang, J. M. Herbert; Section 9.4).
ROKS method for
-SCF calculations of excited states (T. Kowalczyk, T. Van Voorhis; Section 6.5). PARI-K fast exchange algorithm (S. F. Manzer; M. Head-Gordon; Section 4.6.9).
Fragment-based initial guess for SCF methods (Section 12.3).
Pseudo-fractional occupation number method for improved SCF convergence in small-gap systems (D. S. Lambrecht; Section 4.5.8).
Density embedding scheme (B. J. Albrecht, E. Berquist, D. S. Lambrecht; Section 11.6).
New features and enhancements in fragment-based many-body expansion methods (K. U. Lao, J. M. Herbert):
XSAPT(KS)+D: A dispersion corrected version of symmetry-adapted perturbation theory for fast and accurate calculation of interaction energies in non-covalent clusters (Section 12.9).
A preliminary implementation of the many-body body expansion and the fragment molecular orbital methods for clusters (Section 12.10).
Periodic boundary conditions with proper Ewald summation, for energies only (Z. C. Holden, J. M. Herbert; Section 11.3).
1.6.3 New Features in Q-Chem 4.1
New features, enhancements, and bug fixes in Q-Chem 4.1 are as follows.
Fundamental algorithms
Improved parallel performance at all levels including new OpenMP capabilities for Hartree-Fock, DFT, MP2, integral transformation and coupled cluster theory (Z. Gan, E. Epifanovsky, M. Goldey, Y. Shao; Section 2.7.1).
Significantly enhanced ECP capabilities, including availability of gradients and frequencies in all basis sets for which the energy can be evaluated (Y. Shao, M. Head-Gordon; Chap. 8).
Self-Consistent Field and Density Functional Theory capabilities
Numerous DFT enhancements and new features: TD-DFT energy with M06, M08, and M11-series of functionals; XYGJ-OS analytical energy gradient
TD-DFT/C-PCM excitation energies, gradient, and Hessian (J. Liu, W. Liang; Section 6.3.4).
Additional features in the Maximum Overlap Method (MOM) approach for converging difficult DFT and SCF calculations (N. A. Besley; Section 4.5.6).
Wave function correlation capabilities
Resolution-of-identity/Cholesky decomposition implementation of all coupled-cluster and equation-of-motion methods enabling applications to larger systems, reducing disk and memory requirements, and improving performance (E. Epifanovsky, X. Feng, D. Zuev, Y. Shao, A. I. Krylov; Sections 5.7.5 and 5.7.6).
Attenuated MP2 theory in the aug-cc-pVDZ and aug-cc-pVTZ basis sets, which truncate two-electron integrals to cancel basis set superposition error, yielding results for intermolecular interactions that are much more accurate than standard MP2 in the same basis sets (M. Goldey, M. Head-Gordon; Section 5.6.1).
Extended RAS-nSF methodology for ground and excited states involving strong non-dynamical correlations (P. M. Zimmerman, D. Casanova, M. Head-Gordon; Section 6.9).
Coupled cluster valence bond (CCVB) method for describing molecules with strong spin correlations (D. W. Small, M. Head-Gordon; Section 5.14.2).
Walking on potential energy surfaces
Potential energy surface scans (Y. Shao; Section 9.3).
Improvements in automatic transition structure search algorithms by the freezing string method, including the ability to perform such calculations without a Hessian calculation (S. M. Sharada, M. Head-Gordon; Section 9.7).
Enhancements to partial Hessian vibrational analysis (N. A. Besley; Section 10.13.1).
Calculating and characterizing inter- and intra-molecular interactions
Extension of EFP to macromolecules: fEFP approach (A. Laurent, D. Ghosh, A. I. Krylov, L. V. Slipchenko; Section 11.5.3).
Symmetry-adapted perturbation theory level at the “SAPT0” level, for intermolecular interaction energy decomposition analysis into physically-meaningful components such as electrostatics, induction, dispersion, and exchange. A resolution-of-identity implementation is also available (L. D. Jacobson, J. M. Herbert; Section 12.8).
The “explicit polarization” (XPol) monomer-based SCF calculations to compute many-body polarization effects in linear-scaling time via charge embedding (Section 12.7), which can be combined either with empirical potentials (e.g., Lennard Jones) for the non-polarization parts of the intermolecular interactions, or better yet, with SAPT for an ab initio approach called XSAPT that extends SAPT to systems containing more that two monomers (L. D. Jacobson, J. M. Herbert; Section 12.9).
Extension of the absolutely-localized-molecular-orbital-based energy decomposition analysis to unrestricted cases (P. R. Horn, M. Head-Gordon; Section 12.5).
Calculations of populations of effectively unpaired electrons in low-spin state within DFT, a new method of evaluating localized atomic magnetic moments within Kohn-Sham without symmetry breaking, and Mayer-type bond order analysis with inclusion of static correlation effects (E. I. Proynov; Section 10.19).
Calculations of quantum transport including electron transmission functions and electron tunneling currents under applied bias voltage (B. D. Dunietz, N. Sergueev; Section 10.20).
Searchable online version of our PDF manual (J. M. Herbert).
1.6.4 New Features in Q-Chem 4.0.1
Q-Chem 4.0.1 provides several bug fixes, performance enhancements, and the following new features:
Remote submission capability in IQmol (A. T. B. Gilbert).
Scaled nuclear charge and charged cage stabilization capabilities (T. Kús, A. I. Krylov; Section 6.7.6).
Calculations of excited state properties including transition dipole moments between different excited states in CIS and TDDFT as well as couplings for electron and energy transfer (Section 10.18).
1.6.5 New Features in Q-Chem 4.0
Q-Chem 4.0 provides the following new features and upgrades:
Exchange-Correlation Functionals
Density functional dispersion with implementation of the efficient Becke and Johnson’s XDM model in the analytic form (Z. Gan, E. I. Proynov, J. Kong; Section 4.3.7).
Implementation of the van der Waals density functionals vdW-DF-04 and vdW-DF-10 of Langreth and co-workers (O. Vydrov; Section 4.3.5).
VV09 and VV10, new analytic dispersion functionals (O. Vydrov, T. Van Voorhis; Section 4.3.5)
Implementation of DFT-D3 Methods for improved non-covalent interactions (S.-P. Mao, J.-D. Chai; Section 4.3.8).
- B97X-2, a double-hybrid functional based on long range corrected B97 functional with improved account for medium and long range interactions (J.-D. Chai, M. Head-Gordon; Section 4.3.9).
XYGJ-OS, a double-hybrid functional for predictions of nonbonding interactions and thermochemistry at nearly chemical accuracy (X. Xu, W. A. Goddard, Y. Jung; Section 4.3.9).
Calculation of near-edge X-ray absorption with short-range corrected DFT (N. A. Besley).
Improved TDDFT predictions with asymptotically-corrected exchange-correlation potential, TDDFT/TDA with LB94 (Y.-C. Su, J.-D. Chai; Section 4.3.10.1).
Non-dynamical correlation in DFT with efficient RI implementation of Becke05 model in fully analytic formulation (E. I. Proynov, Y. Shao, F. Liu, J. Kong; Section 4.3.3).
Implementation of meta-GGA functionals TPSS and its hybrid version TPSSh (F. Liu) and the rPW86 GGA functional (O. Vydrov).
Implementation of double hybrid functional B2PLYP-D (J.-D. Chai).
Implementation of Mori-Sánchez–Cohen–Yang (MCY2) hyper-GGA functional (F. Liu).
SOGGA, SOGGA11 and SOGGA11-X family of GGA functionals (R. Peverati, Y. Zhao, D. G. Truhlar).
M08-HX and M08-SO suites of high HF exchange meta-GGA functionals (Y. Zhao, D. G. Truhlar)
M11-L and M11 suites of meta-GGA functionals (R. Peverati, Y. Zhao, D. G. Truhlar).
DFT Algorithms
Fast numerical integration of exchange-correlation with multiresolution exchange-correlation, mrXC (S. T. Brown, C.-M. Chang, J. Kong; Section 4.6.7).
Efficient computation of the exchange-correlation part of the dual basis DFT (Z. Gan, J. Kong; Section 4.4.5).
Fast DFT calculation with “triple jumps” between different sizes of basis set and grid and different levels of functional (J. Deng, A. T. B. Gilbert, P. M. W. Gill; Section 4.8).
Faster DFT and HF calculation with atomic resolution of the identity (ARI) algorithms (A. Sodt, M. Head-Gordon).
Post-Hartree–Fock: Coupled Cluster, Equation of Motion, Configuration Interaction, and Algebraic Diagrammatic Construction Methods.
Significantly enhanced coupled-cluster code rewritten for better performance and multicore systems for many modules, including energy and gradient calculations with CCSD and energy calculations with EOM-EE/SF/IP/EA-CCSD, and CCSD(T) energy (E. Epifanovsky, M. Wormit, T. Kús, A. Landau, D. Zuev, K. Khistyaev, I. Kaliman, A. I. Krylov, A. Dreuw; Chaps. 5 and 6). This new code is named CCMAN2.
Fast and accurate coupled-cluster calculations with frozen natural orbitals (A. Landau, D. Zuev, A. I. Krylov; Section 5.10).
Correlated excited states with the perturbation-theory based, size consistent ADC scheme of second order (M. Wormit, A. Dreuw; Section 6.8).
Restricted active space spin flip method for multi-configurational ground states and multi-electron excited states (P. M. Zimmerman, F. Bell, D. Casanova, M. Head-Gordon; Section 6.2.4).
Post-Hartree–Fock methods for describing strong correlation
DFT Excited States and Charge Transfer
Nuclear gradients for excited states with TDDFT (Z. Gan, C.-P. Hsu, A. Dreuw, M. Head-Gordon, J. Kong; Section 6.3.1).
Direct coupling of charged states for study of charge transfer reactions (Z.-Q. You, C.-P. Hsu; Section 10.18.2).
Analytical excited-state Hessian in TDDFT within Tamm-Dancoff approximation (J. Liu, W. Liang; Section 6.3.5).
Obtaining an excited state self-consistently with MOM, the Maximum Overlap Method; see Section 6.4 (Gilbert, Besley, Gill).
Calculation of reactions with configuration interactions of charge-constrained states with constrained DFT (Q. Wu, B. Kaduk, T. Van Voorhis; Section 4.9).
Overlap analysis of the charge transfer in a excited state with TDDFT (N. A. Besley; Section 6.3.2).
Localizing diabatic states with Boys or Edmiston-Ruedenberg localization scheme for charge or energy transfer (J. E Subotnik, R. P. Steele, N. Shenvi, A. Sodt; Section 10.18.1.2).
Implementation of non-collinear formulation extends SF-TDDFT to a broader set of functionals and improves its accuracy (Y. Shao, Y. A. Bernard, A. I. Krylov; Section 6.3)
Solvation and Condensed-Phase Modeling
Smooth free energy surface for solvated molecules via switching/Gaussian polarizable continuum models (SWIG-PCMs), for QM and QM/MM calculations, including a linear-scaling QM/MM/PCM algorithm (A. W. Lange, J. M. Herbert; Sections 11.2.2 and 11.2.4).
The original COSMO solvation model by Klamt, with DFT energy and gradient (ported by Y. Shao; Section 11.2.6).
Accurate and fast energy computation for large systems including polarizable explicit solvation for ground and excited states with effective fragment potential using DFT/TDDFT, CCSD/EOM-CCSD, as well as CIS and CIS(D); library of effective fragments for common solvents; and energy and gradient for EFP-EFP calculations (V. Vanovschi, D. Ghosh, I. Kaliman, D. Kosenkov, C. F. Williams, J. M. Herbert, M. S. Gordon, M. W. Schmidt, Y. Shao, L. V. Slipchenko, A. I. Krylov; Section 11.5).
Optimizations, Vibrations, and Dynamics
Freezing and Growing String Methods for efficient automatic reaction path finding (A. Behn, P. M. Zimmerman, A. T. Bell, M. Head-Gordon; Section 9.6).
Improved robustness of the intrinsic reaction coordinate (IRC)-following code (M. Head-Gordon).
Exact, quantum mechanical treatment of nuclear motions at equilibrium with path integral methods (R. P. Steele; Section 9.10).
Calculation of local vibrational modes of interest with partial Hessian vibrational analysis (N. A. Besley; Section 10.13.1).
Ab initio molecular dynamics with extrapolated
-vector techniques for MP2 and/or dual-basis methods (R. P. Steele; Section 4.7.5). Quasiclassical ab initio molecular dynamics (D. S. Lambrecht, M. Head-Gordon; Section 9.9.4).
Fragment-Based Methods
Symmetry-adapted perturbation theory (SAPT) for computing and analyzing dimer interaction energies (L. D. Jacobson, M. A. Rohrdanz, J. M. Herbert; Section 12.8).
A many-body generalization of SAPT, with empirical dispersion corrections for high accuracy and low cost in large clusters (L. D. Jacobson, K. U. Lao, J. M. Herbert; Section 12.9).
Methods based on the a truncated many-body expansion, including the fragment molecular orbital (FMO) method (K. U. Lao, J. M. Herbert; Section 12.10).
Properties and Wavefunction Analysis
Analysis of metal oxidation states via localized orbital bonding analysis (A. J. W. Thom, E. J. Sundstrom, M. Head-Gordon; Section 10.2.5).
Hirshfeld population analysis (S. Yeganeh; Section 10.2.1).
Visualization of non-covalent bonding using Johnson and Yang’s NCI algorithm (Y. Shao; Section 10.6.5).
ESP on a grid for transition densities (Y. Shao; Section 10.7).
Support for Modern Computing Platforms
Efficient multicore parallel CC/EOM/ADC methods.
Better performance for multicore systems with shared-memory parallel DFT and Hartree-Fock (Z. Gan, Y. Shao, J. Kong) and RI-MP2 (M. Goldey and M. Head-Gordon; Section 5.13).
Accelerating RI-MP2 calculation with graphic processing units, GPUs R. Olivares-Amaya, M. Watson, R. Edgar, L. Vogt, Y. Shao, A. Aspuru-Guzik; Section 5.5.4).
Graphical User Interface
Input file generation, Q-Chem job submission, and visualization is supported by IQmol, a fully integrated GUI developed by Andrew Gilbert from the Australian National University. IQmol is a free software and does not require purchasing a license. See www.iqmol.org for details and installation instructions.
Other graphic interfaces are also available.
1.6.6 New Features in Q-Chem 3.2
Q-Chem 3.2 provides the following important upgrades:
Several new DFT options:
Long-ranged corrected (LRC) functionals (M. A. Rohrdanz, J. M. Herbert)
Baer-Neuhauser-Livshits (BNL) functional (R. Baer, D. Neuhauser, E. Livshits)
Variations of
B97 Functional (J.-D. Chai, M. Head-Gordon) CDFT: Constrained DFT (Q. Wu, T. Van Voorhis)
Grimme’s empirical dispersion correction (C.-D. Sherrill)
Default XC grid for DFT:
Default xc grid is now SG-1. It used to be SG-0 before this release.
Solvation models:
SM8 model (energy and analytical gradient) for water and organic solvents (A. V. Marenich, R. M. Olson, C. P. Kelly, C. J. Cramer, D. G. Truhlar)
Updates to Onsager reaction-field model (C.-L. Cheng, T. Van Voorhis, K. Thanthiriwatte, S. R. Gwaltney)
Intermolecular interaction analysis (R. Z. Khaliullin, M. Head-Gordon):
SCF with absolutely localized molecular orbitals for molecule interaction (SCF-MI)
Roothaan-step (RS) correction following SCF-MI
Energy decomposition analysis (EDA)
Complimentary occupied-virtual pair (COVP) analysis for charge transfer
Automated basis-set superposition error (BSSE) calculation
Electron transfer analysis (Z.-Q. You, C.-P. Hsu)
Relaxed constraint algorithm (RCA) for converging SCF (C.-L. Cheng, T. Van Voorhis)
G3Large basis set for transition metals (V. A. Rassolov)
New MP2 options:
dual-basis RIMP2 energy and analytical gradient (R. P. Steele, R. A. DiStasio Jr., M. Head-Gordon)
O2 energy and gradient (R. C. Lochan, M. Head-Gordon)
New wavefunction-based methods for efficiently calculating excited state properties (D. Casanova, Y. M. Rhee, M. Head-Gordon):
SOS-CIS(D) energy for excited states
SOS-CIS(D
) energy and gradient for excited states
Coupled-cluster methods (P. A. Pieniazek, E. Epifanovsky, A. I. Krylov):
IP-CISD energy and gradient
EOM-IP-CCSD energy and gradient
OpenMP for parallel coupled-cluster calculations
QM/MM methods (H. L. Woodcock, A. Ghysels, Y. Shao, J. Kong, H. B. Brooks)
QM/MM full Hessian evaluation
QM/MM mobile-block Hessian (MBH) evaluation
Description for MM atoms with Gaussian-delocalized charges
Partial Hessian method for vibrational analysis (N. A. Besley)
Wavefunction analysis tools:
Improved algorithms for computing localized orbitals (J. E. Subotnik, Y. M. Rhee, A. J. W. Thom, W. Kurlancheek, M. Head-Gordon)
Distributed multipole analysis (V. Vanovschi, A. I. Krylov, C. F. Williams, J. M. Herbert)
Analytical Wigner intracule (D. L. Crittenden, P. M. W. Gill)
1.6.7 New Features in Q-Chem 3.1
Q-Chem 3.1 provides the following important upgrades:
Several new DFT functional options:
The non-empirical GGA functional PBE (from the open DF Repository distributed by the QCG CCLRC Daresbury Lab., implemented in Q-Chem 3.1 by E. I. Proynov).
M05 and M06 suites of meta-GGA functionals for more accurate predictions of various types of reactions and systems (Y. Zhao, N. E. Schultz, D. G. Truhlar).
A faster correlated excited state method: RI-CIS(D) (Y. M. Rhee)
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).
1.6.8 New Features in Q-Chem 3.0
Q-Chem 3.0 includes many new features, along with many enhancements in performance and robustness over previous versions. Below is a list of some of the main additions, and who is primarily to thank for implementing them. Further details and references can be found in the official citation for Q-Chem (see Section 1.8).
Improved two-electron integrals package (Y. Shao):
Code for the Head-Gordon–Pople algorithm rewritten to avoid cache misses and to take advantage of modern computer architectures.
Overall increased in performance, especially for computing derivatives.
Fourier Transform Coulomb method (L. Fusti-Molnar):
Highly efficient implementation for the calculation of Coulomb matrices and forces for DFT calculations.
Linear scaling regime is attained earlier than previous linear algorithms.
Present implementation works well for basis sets with high angular momentum and diffuse functions.
Improved DFT quadrature evaluation:
Incremental DFT method avoids calculating negligible contributions from grid points in later SCF cycles (S. T. Brown).
Highly efficient SG-0 quadrature grid with approximately half the accuracy and number of grid points as the SG-1 grid (S.-H. Chien).
Dual basis self-consistent field calculations (J. Kong, R. P. Steele):
Two stage SCF calculations can reduce computational cost by an order of magnitude.
Customized basis subsets designed for optimal projection into larger bases.
Auxiliary basis expansions for MP2 calculations:
RI-MP2 and SOS-MP2 energies (Y. Jung) and gradients (R. A. DiStasio Jr.).
RI-TRIM MP2 energies (R. A. DiStasio Jr.).
Scaled opposite spin energies and gradients (R. C. Lochan).
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/ROHF references.
Analytic gradients and properties calculations (permanent and transition dipoles etc.).
Full use of Abelian point-group symmetry.
Singlet strongly orthogonal geminal (SSG) methods (V. A. Rassolov).
Coupled-cluster perfect-paring methods (M. Head-Gordon):
Perfect pairing (PP), imperfect pairing (IP) and restricted pairing (RP) models.
PP(2) Corrects for some of the worst failures of MP2 theory.
Useful in the study of singlet molecules with diradicaloid character.
Applicable to systems with more than 100 active electrons.
Hybrid quantum mechanics /molecular mechanics (QM/MM) methods:
Fixed point-charge model based on the Amber force field.
Two-layer ONIOM model (Y. Shao).
Integration with the Molaris simulation package (E. Rosta).
Q-Chem/Charmm interface (H. L. Woodcock)
New continuum solvation models (S. T. Brown):
Chipman’s Surface and Simulation of Volume Polarization for Electrostatics [SS(V)PE] model.
Available for HF and DFT calculations.
New transition structure search algorithms (A. Heyden and B. Peters):
Growing string method for finding transition states.
Dimer Method which does not use the Hessian and is therefore useful for large systems.
Ab initio molecular dynamics (J. M. Herbert):
Available for SCF wavefunctions (HF, DFT).
Direct Born-Oppenheimer molecular dynamics (BOMD).
Extended Lagrangian ab initio molecular dynamics (ELMD).
Linear scaling properties for large systems (J. Kussmann, C. Ochsenfeld):
NMR chemical shifts.
Static and dynamic polarizabilities.
Static hyperpolarizabilities, optical rectification and electro-optical Pockels effect.
Anharmonic frequencies (C. Y. Lin):
Efficient implementation of high-order derivatives
Corrections via perturbation theory (VPT) or configuration interaction (VCI).
New transition optimized shifted Hermite (TOSH) method.
Wavefunction analysis tools:
Spin densities at the nuclei (V. A. Rassolov).
Efficient calculation of localized orbitals.
Optimal atomic point-charge models for densities (A. C. Simmonett).
Calculation of position, momentum and Wigner intracules (N. A. Besley, D. P. O’Neill).
Graphical user interface options:
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).
Support for the public domain version of WebMO (see www.webmo.net).
Seamless integration with the Spartan package (see www.wavefun.com).
Support for the public domain version of Avogadro (see:
http://avogadro.openmolecules.net/wiki/Get_Avogadro).Support the MolDen molecular orbital viewer (see www.cmbi.ru.nl/molden).
Support the JMol package (see http://sourceforge.net/project/showfiles.php?group_id= 23629&release_id=66897).
1.6.9 Summary of Features Prior to Q-Chem 3.0
Efficient algorithms for large-molecule density functional calculations:
CFMM for linear scaling Coulomb interactions (energies and gradients) (C. A. White).
Second-generation J-engine and J-force engine (Y. Shao).
LinK for exchange energies and forces (C. Ochsenfeld and C. A. White).
Linear scaling DFT exchange-correlation quadrature.
Local, gradient-corrected, and hybrid DFT functionals:
Slater, Becke, GGA91 and Gill ‘96 exchange functionals.
VWN, PZ81, Wigner, Perdew86, LYP and GGA91 correlation functionals.
EDF1 exchange-correlation functional (R. Adamson).
B3LYP, B3P and user-definable hybrid functionals.
Analytical gradients and analytical frequencies.
SG-0 standard quadrature grid (S.-H. Chien).
Lebedev grids up to 5294 points (S. T. Brown).
High level wavefunction-based electron correlation methods (Chapter 5):
Efficient semi-direct MP2 energies and gradients.
MP3, MP4, QCISD, CCSD energies.
OD and QCCD energies and analytical gradients.
Triples corrections (QCISD(T), CCSD(T) and OD(T) energies).
CCSD(2) and OD(2) energies.
Active space coupled cluster methods: VOD, VQCCD, VOD(2).
Local second order Møller-Plesset (MP2) methods (DIM and TRIM).
Improved definitions of core electrons for post-HF correlation (V. A. Rassolov).
Extensive excited state capabilities:
CIS energies, analytical gradients and analytical frequencies.
CIS(D) energies.
Time-dependent density functional theory energies (TDDFT).
Coupled cluster excited state energies, OD and VOD (A. I. Krylov).
Coupled-cluster excited-state geometry optimizations.
Coupled-cluster property calculations (dipoles, transition dipoles).
Spin-flip calculations for CCSD and TDDFT excited states (A. I. Krylov and Y. Shao).
High performance geometry and transition structure optimization (J. Baker):
Optimizes in Cartesian, Z-matrix or delocalized internal coordinates.
Impose bond angle, dihedral angle (torsion) or out-of-plane bend constraints.
Freezes atoms in Cartesian coordinates.
Constraints do not need to be satisfied in the starting structure.
Geometry optimization in the presence of fixed point charges.
Intrinsic reaction coordinate (IRC) following code.
Evaluation and visualization of molecular properties
Onsager, SS(V)PE and Langevin dipoles solvation models.
Evaluate densities, electrostatic potentials, orbitals over cubes for plotting.
Natural Bond Orbital (NBO) analysis.
Attachment /detachment densities for excited states via CIS, TDDFT.
Vibrational analysis after evaluation of the nuclear coordinate Hessian.
Isotopic substitution for frequency calculations (R. Doerksen).
NMR chemical shifts (J. Kussmann).
Atoms in Molecules (AIMPAC) support (J. Ritchie).
Stability analysis of SCF wavefunctions (Y. Shao).
Calculation of position and momentum molecular intracules A. Lee, N. A. Besley, D. P. O’Neill).
Flexible basis set and effective core potential (ECP) functionality: (Ross Adamson and Peter Gill)
Wide range of built-in basis sets and ECPs.
Basis set superposition error correction.
Support for mixed and user-defined basis sets.
Effective core potentials for energies and gradients.
Highly efficient PRISM-based algorithms to evaluate ECP matrix elements.
Faster and more accurate ECP second derivatives for frequencies.