Explore Q-Chem Features
Q-Chem is a robust software platform with an extensive set of features. Whether you want to study spin-orbit coupling effects in a single-molecule magnet, run high-throughput calculations on small organic molecules, study an enzyme using QM/MM, or something entirely different, our software package offers a wide range of solutions for a variety of applications. Check out our available features and see how Q-Chem can help you achieve your research goals!
Q-Chem supports LDA, GGA, and meta-GGA functionals, as well as 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.
We are pleased to present the seventh major release of the Q-Chem ab inito quantum chemistry software package, Q-Chem 6.2! Our latest release has many improvements and new features, including:
- Natural Auger Orbitals for Auger decay, ICD, and related processes for CVS-EOM methods (Nayanthara K. Jayadev, Anna I. Krylov)
- ACP-EOMIP-CCSD for partial Auger decay widths (Florian Matz, Thomas Jagau)
- EOM-CCSDT for EE and SF states (Manisha, Prashant Uday Manohar)
- Dipole filtering for TDKS (John Herbert, Avik Kumar Ojha)
- DFT/CIS semi-empirical method, including a new parameterization for X-ray spectroscopy (Aniket Mandal, John Herbert)
- Generalization of 1C-NOCIS to two-electron open-shell singlets (Juanes Arias-Martinez, Hamlin Wu, Martin Head-Gordon)
- Atomic multipole moment calculation using IAOs (Alexandra McIsaac, Abdulrahman Aldossary, Martin Head-Gordon)
- RT-NEO, RT-NEO-Ehrenfest, BO-RT-NEO-Ehrenfest, and RT-NEO-Ehrenfest-QM/MM (Tao E. Li, Mathew Chow, and Sharon Hammes-Schiffer)
- NEO multistate DFT (NEO-MSDFT) (Joseph Dickinson, Qi Yu, and Sharon Hammes-Schiffer)
- SCS-RIMP2 and SOS-OOMP2 for NEO methods (Jonathan Fetherolf and Sharon Hammes-Schiffer)
For a complete list of new features, bugfixes, and improvements, please see the Q-Chem 6.2 release log. Interested in trying our new features? Request a free two-month demo here!
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 for studying 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. Additionally, our wavefunction analysis module can be used to provide further insight into excited states.
![QM/MM Embedding](/sites/default/files/styles/large/public/2021-05/solvation_tmp2.png?itok=ptbEbvQU)
QM/MM Embedding
![PCM Solvation](/sites/default/files/styles/large/public/2021-05/solv-2.png?itok=B8GnPFdY)
PCM Solvation
![EFP for Solvated Species](/sites/default/files/styles/large/public/2021-05/solvation_tmp2-2.png?itok=8HTFUpqC)
EFP for Solvated Species
The Q-Chem package offers a variety of solutions for modeling solvated systems, ranging from implicit solvent models, such as SM8, COSMO, and C-PCM, to the effective fragment potential method, which can be used to capture explicit solvent effects. Additionally, Q-Chem includes several different embedding approaches, including QM/MM and density embedding, as well as interfaces to CHARMM and GROMACS.
![Vibrational Spectroscopy](/sites/default/files/styles/large/public/2021-05/spec_vib.pdf_2.png?itok=OuIaCfFG)
Vibrational Spectroscopy
![Electronic Spectroscopy](/sites/default/files/styles/large/public/2021-05/prydine-UVVis-2.png?itok=LXEXegAc)
Electronic Spectroscopy
![Vibronic Spectroscopy](/sites/default/files/styles/large/public/2021-05/Franck_Condon_Diagram-2.png?itok=89xWAeM0)
Vibronic Spectroscopy
![X-ray Spectroscopy](/sites/default/files/styles/large/public/2021-05/X-ray-2.png?itok=2BQtdCIj)
X-ray Spectroscopy
![Photoelectron Spectroscopy](/sites/default/files/styles/large/public/2021-05/PE-2.png?itok=HOk5CI9r)
Photoelectron Spectroscopy
![Magnetic Spectroscopy](/sites/default/files/styles/large/public/2021-05/NMR_2.png?itok=x3j9_bA5)
Magnetic Spectroscopy
![Nonlinear Spectroscopy](/sites/default/files/styles/large/public/2021-05/2DIR-2.png?itok=DZZjdPhE)
Nonlinear Spectroscopy
Q-Chem offers a variety of tools for modeling different types of spectra. Our capabilities include IR and Raman spectroscopy, UV-vis spectroscopy, X-ray spectroscopy, photoelectron spectroscopy, NMR spectroscopy, and nonlinear spectroscopy (such as two-photon absorption). Spectroscopic features can be studied using many different levels of theory, ranging from TDDFT to EOM-CC and ADC methods.
![Energy Decomposition Analysis](/sites/default/files/styles/large/public/2021-05/39_2.png?itok=jLJK6G5s)
Energy Decomposition Analysis
![ALMO-EDA for the AT Complex](/sites/default/files/styles/large/public/2021-05/eda1-2.png?itok=vtWlezYc)
ALMO-EDA for the AT Complex
![EDA for a Ru Complex](/sites/default/files/styles/large/public/2021-05/eda2-2.png?itok=zh-MVABK)
EDA for a Ru Complex
![Comparison of Errors](/sites/default/files/styles/large/public/2021-05/38-2.png?itok=GItyyyTe)
Comparison of Errors
![SAPT](/sites/default/files/styles/large/public/2021-05/sapt-2.png?itok=9pWk7UsU)
SAPT
![XSAPT](/sites/default/files/styles/large/public/2021-05/xsapt-2.png?itok=BHOzEqiP)
XSAPT
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.
Q-Chem provides methods for geometry optimization, potential energy surface scans, transition state searches, and intrinsic reaction coordinate following, making it ideal for studies of chemical reactivity, thermochemistry, and chemical kinetics.
![](/sites/default/files/styles/large/public/2021-05/aimd1-2.png?itok=vNSf24YK)
![](/sites/default/files/styles/large/public/2021-05/aimd2-2.png?itok=a8kGF3f3)
![](/sites/default/files/styles/large/public/2021-05/aimd3-2.png?itok=r1dkTOZc)
Q-Chem can perform ab initio molecular dynamics (AIMD), including both NVE and NVT thermal samplings, as well as quasi-classical molecular dynamics (QMD). These approaches can be used to produce vibrational spectra and ab initio path integrals. We also include an implementation of Tully's fewest-switches surface hopping (FSSH) approach to effectively handle non-adiabatic systems.