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1.3 Q-Chem Features

1.3.2 New Features in Q-Chem 6.3

(May 21, 2025)

1.3.2.1 Features in 6.3.0

  • Changes to keywords and default behavior:

    • Use MDQ-uFERF as default for EDA2 jobs (EDA_UFERF = TRUE) (Hengyuan Shen, Abdulrahman Aldossary, Martin Head-Gordon)

    • Add REM control option for fragment CPSCF max iterations (FRAG_CPSCF_MAXITER) (Yuezhi Mao)

    • Change alpha in BW-s2 jobs to n/1000 rather than n/100 (Linus Dittmer, Nikolay V. Tkachenko, Martin Head-Gordon)

    • Make O-V projection the default for basis2 calculations (BASISPROJTYPE = OVPROJECTION) (Kuan-Yu Liu)

    • All NEO jobs will now use a tight initial guess by default (Mathew Chow, Sharon Hammes-Schiffer)

    • Use nuclear core guess by default for NEO jobs with ghost atoms (Mathew Chow, Sharon Hammes-Schiffer)

    • Use simultaneous SCF by default for NEO calculations (NEO_SIMULTANEOUS_SCF = TRUE) (Mathew Chow, Sharon Hammes-Schiffer)

  • General features and improvements:

    • MPI parallelization for finite-difference and many-body expansion calculations (Kaushik Nanda)

    • Added torsional and flat-bottom potential restraints for geometry optimizations (Chance W. Lander, Yihan Shao)

    • Added bond stretch, r12pr34, angle, 1 to midpoint of 2 atoms, 1 to COM, and dihedral restraints to list of available restrained PES scan options (Chance W. Lander, Yihan Shao)

    • Re-enabled NTOs for RPAs, corrected to use proper particle and hole density matrices (John Herbert)

    • New mechanochemical pressure model using PV term energy correction (Felix Zeller)

    • Resolved issues with:

      • *

        Hessian calculation rerun unnecessarily when GEOM_OPT_HESSIAN = READ in libopt3 (Yuezhi Mao)

      • *

        Remove bottlenecks in electronic JK gradient evaluation in libneo and librtneo (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Eliminate NaN values in Feshbach-Fano calculations for large, diffuse basis sets (Saikat Roy, Wojciech Skomorowski)

      • *

        Fix orbitals not being printed to .fchk file used by IQmol (Kuan-Yu Liu)

      • *

        Enable FAST_XAS crash with STATE_ANALYSIS = TRUE or GUI = 2 (Kaushik Nanda)

      • *

        Fix incompatibility of SCF_FINAL_PRINT and DC-DFT (John Herbert)

      • *

        Fix failure to conserve molecular point-group symmetry in libopt3 (Andrew Gilbert)

      • *

        Fix file error when calculating TS-VDW forces (John Herbert)

  • Density functional theory and self-consistent field:

    • New “Robust SCF” procedure provides more reliable SCF convergence via automated choice of algorithm and defaults (Kaushik Nanda)

    • Performance enhancements for medium to large DFT calculations (Xintian Feng)

    • Canonical ROHF/ROSCF (Adrian L. Dempwolff)

    • Charge-transfer metrics for TDDFT (John Herbert)

    • TDDFT-1D provides improved TDDFT/TDA where the crossing of S1/S0 states is smooth (Vishikh Athavale, Hung-Hsuan Teh, Joseph Subotnik)

    • Resolved issues with:

      • *

        Crash of ALMO-CIS/TDA with large basis sets (Yuezhi Mao)

      • *

        DFT numerical quadrature consistency check not always performed (Xintian Feng)

  • Correlated methods:

    • EOM-CCSDT for EE, SF, IP, EA, DIP and DEA (Manisha, Prashant Uday Manohar)

    • Added parallel performance to EOM-CCSDT (Manisha)

    • Analytic gradients for EOM-DEA/DIP-CCSD methods (Tingting Zhao, Anna Krylov)

    • SOC and <S2> calculations for EOM-DEA/DIP-CCSD methods (Tingting Zhao, Sai Kotaru, Sahil Gulania, Pavel Pokhilko, Anna Krylov)

    • Automated calculations of Coulomb wave for caluclations of Auger rates within the Feshbach–Fano framework (Saikat Roi, Wojciech Skomorowski)

    • Auger Channel Projection EOMIP-CCSD with frozen core and open shell references (Robin Moorby, Florian Matz, Thomas Jagau)

    • Complex-valued RI-EOM-CCSD (Simen Camps, Cansu Utku, Thomas Jagau)

    • EOM-(EE/SF)-CCSD dynamic polarizability for imaginary frequencies (Kaushik Nanda)

    • Improved EOM-CC anisotropic polarizability formula (Kaushik Nanda)

    • CC2 with size-consistent Brillouin–Wigner Partitioning (Linus Dittmer, Nikolay V. Tkachenko, Martin Head-Gordon)

    • Maximum Physical Regularization for size-consistent Brillouin-Wigner Theory (Linus Dittmer, Nikolay V. Tkachenko, Martin Head-Gordon)

    • BW-S2 performance improvements (Zhenling Wang, Martin Head-Gordon)

    • Extend 1eX2C to calculate spin-orbit coupling components (Richard Kang, Martin Head-Gordon)

    • New algorithm to accelerate 1C-NOCIS calculations using generalized non-orthogonal Slater-Condon rules (Rachel Lynn Patterson, Martin Head-Gordon)

    • Implementation of coupling between Dyson orbitals and the continuum (plane wave) (Madhubani Mukherjee, Anna I. Krylov)

    • Add a switch to control averaging in DO/PW coupling calculation (Madhubani Mukherjee, Anna I. Krylov)

    • Resolved issues with:

      • *

        Coupled cluster PES scans erroneously reporting SCF energy (Kaushik Nanda)

      • *

        Convergence difficulties in DIP-EOM-CCSDT (Manisha)

      • *

        Crash due to memory allocation issues in Auger decay width calculations for certain basis sets (Saikat Roy, Wojciech Skomorowski)

  • Molecular dynamics, non-adiabatic dynamics, embedding, and solvation:

    • SAPT+PCM, dielectric boundaries for (X)SAPT calculations (John Herbert)

    • Heterogeneous PCM allows users to modify the dielectric for each atom in PCM (John Herbert)

    • Seminumerical frequency support for the SMD solvation model (John Herbert)

    • Energy-based generalized many-body expansion (GMBE) implementation (Jake A. Tan, Francisco Ballesteros, Ka Un Lao)

    • Density matrix-based generalized many-body expansion (GMBE) implementation (Jake A. Tan, Francisco Ballesteros, Ka Un Lao)

    • Allow user-defined vdW radii for Poisson equation solver, PEqS (John Herbert)

    • Enable user to explicitly set polarization screening factor in EFP (Kaushik Nanda)

    • Resolved issues with:

      • *

        Many-body calculations with gradients fail with FILE_MO_COEFS error (Kaushik Nanda, Ryan Steele)

      • *

        Missing EFP polarization energy at every SCF step when USE_LIBQINTS = TRUE (Xintian Feng)

      • *

        Disabled NAC calculations with SMD (John Herbert)

      • *

        Printing spatial overlaps of occ-virt orbital pairs, SPATIAL_OVERLAP_ANALYSIS (John Herbert)

  • Fragment and energy decomposition analysis:

    • Broken bond orbitals (BBOs) (Alistair J. Sterling, Daniel S. Levine, Abdul Aldossary, Martin Head-Gordon)

    • Enable ALMO(MSDFT) diabatic coupling calculation involving Delta-SCF excited states (Yuezhi Mao)

    • Uncoupled FERF (Hengyuan Shen, Abdul Aldossary, Martin Head-Gordon)

  • Incorporation of quantum nuclear effects (NEO suite):

    • NEO-PCM analytic Hessian for solution phase frequency and normal mode analysis (Mathew Chow, Sharon Hammes-Schiffer)

    • External point charges are now supported for NEO electrostatic embedding calculations (Mathew Chow, Sharon Hammes-Schiffer)

    • Enabled exchange-correlation functionals that have additional dispersion correction baked-in (e.g., wB97X-D, wB97X-D3, B3LYP-D3(BJ), etc.) to be used in NEO-DFT (Mathew Chow, Sharon Hammes-Schiffer)

    • Added full DFT-D support for NEO (energies, gradients, Hessians) and RT-NEO (real-time and real-time-Ehrenfest) calculations (Mathew Chow, Sharon Hammes-Schiffer)

    • Pseudopotentials are now fully supported with NEO (including energies, gradients, and Hessians) (Mathew Chow, Sharon Hammes-Schiffer)

    • DIIS_GDM is now supported for the NEO simultaneous solver (Mathew Chow, Sharon Hammes-Schiffer)

    • Improved performance by:

      • *

        Simultaneous GDM optimization for NEO-HF and NEO-DFT methods (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Nuclear SCF initial guess (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Generalized simultaneous DIIS and GDM optimization to treat ’N’ number of quantum protons to achieve faster NEO Hartree Product calculations (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Various improvements to simultaneous NEO-PCM calculations, including support with Hartree product and multiple proton CNEO Hessian calculations (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Updates and improvements to general orbital optimizer library (Christopher Malbon, Sharon Hammes-Schiffer)

      • *

        Performance improvements to CNEO Hessian calculations via addition of preconditioner (Eno Paenurk, Sharon Hammes-Schiffer)

      • *

        Improved stability and performance for NEO Hessian and CNEO Hessian codes (Mathew Chow, Sharon Hammes-Schiffer)

    • Resolved issues with:

      • *

        Fixed issue where nuclear AUTOSAD would not read NEO_PURECART for child instructions (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Fixed issue where MAX_SCF_CYCLES did not have an effect on the simultaneous NEO-SCF solvers (Mathew Chow, Sharon Hammes-Schiffer)

      • *

        Fixed memory issue for calculations using NEO simultaneous SCF combined with NEO Hartree product (Mathew Chow, Sharon Hammes-Schiffer)