Explore Q-Chem Features


Highlights of the Q-Chem 5.3 webinar:

  • Support for meta-GGA density functionals in calculations of TDDFT analytic forces and vibrational frequencies

  • Nvidia GPU acceleration of energy, gradients, and frequency calculations with most density functionals (via BrianQC)

  • Cloud computing using Amazon EC2

  • Suite of methods for simulating X-ray spectroscopy

  • Simulation of resonance Raman spectroscopy

  • Level-shifting DIIS for improved SCF convergence in difficult cases

  • Nuclear-electronic orbital methods

Q-Chem 5.3 features faster code for TD-DFT analytic frequencies using global and range-separated GGA and meta-GGA density functionals, as well as many new capabilities and improvements. QMP subscribers can upgrade today at no additional charge. Try Q-Chem today by installing a free Q-Chem demo.

Q-Chem supports LDA, GGA, and meta-GGA functionals, plus hybrid, range-separated hybrid, and double hybrid versions of both GGAs and meta-GGAs. Single-point energies, geometry optimizations, vibrational frequency calculations, and many other properties can be evaluated for ground states, and for excited states via time-dependent DFT.


Q-Chem offers state-of-the-art tools for treating electron correlation effects, such as Møller-Plesset perturbation theory and coupled-cluster theory. For systems with strong correlation, Q-Chem offers specialty treatments including CASSCF, coupled-cluster valence bond theory, selected CI, RAS-CI, spin-flip, and variational 2-RDM methods.

Q-Chem provides a diverse set of methods to study electronically excited states: CIS, TD-DFT, NOCI, EOM-CC, and ADC. Specialty flavors of these methods cover many types of electronic structure, making it possible to simulate spectroscopic features, charge and energy transfer, and non-adiabatic dynamics.

Q-Chem offers many tools for modeling spectroscopy, including IR and Raman spectroscopy, UV-vis spectroscopy, X-ray spectroscopy, photoelectron spectroscopy, NMR, and nonlinear spectroscopy (such as two-photon absorption).  These spectroscopy features can be studied at different levels of theory, e.g., ranging from TDDFT to EOM-CC and ADC methods.

Energy decomposition analysis based on absolutely localized molecular orbitals provides a breakdown of the total interaction energy into meaningful physical terms, providing insights into the nature of intermolecular and bonded interactions. Symmetry-adapted perturbation theory (SAPT) and an extended many-body version thereof (XSAPT) are also available for computing and analyzing intermolecular interactions.


Methods for geometry optimization, potential energy surface scans, transition state search, intrinsic reaction coordinate following assist in the studies of chemical reactivity, thermochemistry, and chemical kinetics.