New Features in Q-Chem 7

Q-Chem 7 is coming in July 2026! Q-Chem 7 includes all of the performance and usability features you've come to expect from Q-Chem (like our parallel RI algorithms for fast DFT performance, and our Robust SCF algorithm for easy convergence), along with a plethora of new features.

Get a sneak peek at some of the anticipated new features below!

QC-PBC

QC-PBC is a new module for handling solid-state systems and materials by all-electron calculations with periodic boundary conditions and Gaussian basis sets.

• DFT and TDDFT
• MP2, LT-MP2, and MP3 for gamma and k-point calculations
• CCSD, CCSD(T), and CCSDT for gamma-point calculations
• Python interfacing
• Geometry optimization
• Solvation
• Analytic frequency and phonon calculations

M-Chem

M-Chem is a new module for handling large biomolecular systems.

• High-performance MPI/OpenMP hybrid implementation for molecular dynamics (MD) simulations
• Fixed charge (Amber), polarizable (AMOEBA), and ReaxFF force fields
• Nose-Hoover thermostat and barostats, conjugate gradient self-consistent field and novel extended Lagrangian schemes for solving the many-body forces, periodic boundary conditions, and particle mesh Ewald
• Modular front-end that stream-lines parameter assignment and system preparation in a more user-friendly and reproducible way for standard force fields and protein-water simulations
• QM/MM integration with ReaxFF
• Trajectory formats for analysis in other codes

Density Functional Theory

• COACH functional: A new range-separated hybrid (RSH) meta-GGA that is more accurate and transferable than the best existing RSH meta-GGAs, such as ωB97M-V, for a wide variety of systems. (Jiashu Liang, Martin Head-Gordon)
• Faster MP2 and double-hybrid DFT: New algorithm provides competitive scaling with DLPNO for MP2 and double-hybrid DFT, with improved error control for higher accuracy. (Zhenling Wang, Yao Shen, Martin Head-Gordon)
• ECD with TDDFT (Xunkun Huang, WanZhen Liang) and EOM-CCSD
• New complex-variable DFT functionals for handling electronically metastable states, including LDA (Slater X, VWN5 C, VWN1RPA C), GGA (B88 X, PBE X, PBE C, LYP C) and hybrid (all hybrid functionals composed of the above LDAs and GGAs and possibly exact HF exchange, including PBE0, B3LYP and BH&HLYP). (Charlotte Titeca, Yifan Jiang, Thomas-C. Jagau)
• Extended tight binding DFT (xtb) energy and gradient (Rebecca Tomann, Martin Head-Gordon)

Correlated Methods

• MRSF-TDDFT with properties: MRSF-TDDFT is an improved version of spin-flip TDDFT that enables effectively spin-pure treatments of doubly excited states, bond-breaking, conical intersections, and some other cases of strongly correlated systems. Q-Chem 7 presents effective MRSF-TDDFT implementation including calculation of state and transition properties, such as state and transition dipole moments, oscillator strengths, spin–orbit couplings, and density-matrix based analyses of the MRSF states and transitions. (Arnab Chakraborty, Zheng Pei, Yihan Shao, Anna I. Krylov)
• New excited-state analysis features based on Earth Mover's Distance (Zhe Wang, Martin Head-Gordon)
• Charge-displacement metrics of TDDFT in libwfa. These metrics are based on  are rigorously invariant with respect to orbital rotations, unlike earlier metrics used in other software packages (John Herbert) 
• Large speedups in RI-CC2 ground state code in libgmbpt (Hrishikesh Ram and Martin Head-Gordon)
• CC2 and RI-CC2 Dyson orbitals for EA, IP, EE-EA, and EE-IP (Mauro Gascón Navas, Thomas C. Jagau, Robin E. Moorby, Simen Camps, Tianyi Gao)
• THC-sRI Improvements: Includes RI-CC2 and sRI-CC2 oscillator strengths; THC-sRI-CC2 ground and excited state energies and properties; and THC-sRI-CCSD ground and excited state energies (Chongxiao Zhao, Ruihao Bi, Qi Ou, Joohno Lee, Chenyang Li, Wenjie Dou)
• Performance improvements for RI and CD CCSD and EOM-CCSD
• New tools for calculating Auger decay rates using CC/EOM-CC
• NMR chemical shifts improvements (Xiao Liu, Martin Head-Gordon)
• New MPI/OpenMP parallel finite first differences algorithm using RI gives very large speedups over Q-Chem’s legacy NMR code
• Support for all modern density functionals through hybrids

Molecular Dynamics, Non-adiabatic Dynamics, Embedding, and Solvation

• New embedding interface for external packages like CP2K (Ar Fonlon, Elena Kolodzeiski, Dustin R. Broderick, Kay Carter-Fenk, Christopher J. Mundy, Christopher J. Stein, John M. Herbert)
• An order of magnitude total speed up for large QM/EFP jobs via parallelization of one-electron integrals (Lyudmila Slipchenko)
• Pairwise harmonic confiner for optimization in internal coordinates (Chance Brandt, John Herbert)

Fragment and Energy Decomposition Analysis

• Correlated wavefunction EDA: EDA-II is available for MP2, BW-s2, κ-MP2 using the linear-scaling codebase (Zhenling Wang, Hengyuan Shen, Martin Head-Gordon) 
• EDA OVOCV analysis and OODFT OVOCV analysis: OVOCV can be used to replace or complement NOCV analysis in EDA; it provides clearer identification of donor and acceptor orbitals than NOCV methods. (Hengyuan Shen, Martin Head-Gordon)
• Energy Decomposition Analysis for Restricted Open-shell Kohn-Sham Theory (ROKS-EDA) (Haobo Ling, Hengyuan Shen, Martin Head-Gordon)
• Two new MBD dispersion models for XSAPT+MBD: 
• MBDrev, based on machine learning applied to the SAPT10k data set (Corentin Villot and Ka Un Lao)
• oC8raim, with improved performance for ions and extended to heavy elements (Keegan Paice, John Herbert)

Incorporation of Quantum Nuclear Effects (NEO Suite)

• NEO-AIMD methods for NEO-HF and NEO-DFT, including:
• NEO Born-Oppenheimer MD (NEO-BOMD) (Joseph Dickinson, Sharon Hammes-Schiffer)
• Extended Lagrangian MD (NEO-ELMD) (Joseph Dickinson, Sharon Hammes-Schiffer)
• Constrained NEO MD (CNEO-MD) (Joseph Dickinson, Sharon Hammes-Schiffer)
• NEO-PCM and NEO-QM/MM (Joseph Dickinson, Sharon Hammes-Schiffer)