Q-Chem

Q-Chem 6.4 is here! Upgrade for new spectroscopy features (such as CVS-XCIS our new-and-improved ΔSCF driver), iterative CC-in-DFT embedding, faster CC calculations, MR-SF-DFT, stochastic RI-CC2, NEO methods, and more: q-chem.com/explore/qc64/

Q-Chem's Δ-ALMO(MSDFT2) combines ΔSCF with ALMO to generate diabatic states, then uses MSDFT2 to obtain their couplings with charge-transfer states. Here, developers test Δ-ALMO(MSDFT2) on systems ranging from singlet fission to DNA repair: doi.org/10.1063/5.0035…

New in Q-Chem 7: Excited-state analysis for MRSF-TDDFT, including natural orbitals (NOs), natural transition orbitals (NTOs), natural difference orbitals (NDOs), and related descriptors. Read the developers' recent preprint: doi.org/10.26434/chemr… #compchem

Practical application of Q-Chem's wave-function analysis: Developers use spin-orbit NTO analysis for TDDFT and SF-TDDFT (added in Q-Chem 6.1) to assess the character of different states, allowing them to properly compare spin-orbit coupling results. doi.org/10.1063/5.0130…

Q-Chem 6.3 has new charge-transfer metrics for TDDFT, helping researchers identify orbitals most likely to participate in charge-transfer-to-solvent (CTTS) excitations, with applications to solution-phase chromophores. doi.org/10.1021/acs.jc… Try Q-Chem: q-chem.com/try/

Q-Chem provides a wave-function analysis toolkit (libwfa) that enables visualization of excited states, automatic assignment of properties, and deeper insight into the underlying physics. QC6 has included several new additions, including CT metrics for TDDFT and Δ-ALMO(MSDFT2).

The broken bond orbital (BBO) approach, introduced in QC 6.3, uses an EDA framework to assess key mechanisms at play during bond formation, helping researchers better understand the nature of chemical bonding. Watch the recent webinar here: q-chem.com/webinars/78/

New in Q-Chem 7.0: EDA and OO-DFT OVOCV! Occupied-virtual orbitals for chemical valence (OVOCV) can be used to replace or complement NOCV analysis in EDA; it provides clearer identification of donor and acceptor orbitals than NOCV methods. doi.org/10.1021/acs.jp… #compchem

Force decomposition analysis (FDA) extends EDA to forces, allowing researchers to break force down into different physically-meaningful components. It provides information beyond EDA, including data that can be used to train physics-based #forcefields. pubs.acs.org/doi/10.1021/ac…

Q-Chem's energy decomposition analysis (EDA) tools have seen many improvements in QC6, including POL and NOCV analysis and force decomposition analysis. We're excited to have new EDA features in our upcoming 7.0 release! Learn more about EDA in Q-Chem: manual.q-chem.com/latest/Ch12.S6…

In this recent collaborative preprint, researchers use experimental and theoretical techniques to investigate Norrish Type-I reactions. Q-Chem's OO-DFT is one technique they use to model spectra. arxiv.org/abs/2603.18339 Learn more about OO-DFT in Q-Chem: q-chem.com/webinars/68/

It's still not too late to register for today's webinar! Join us at 11AM Pacific time to learn more from Juan E. Arias Martinez about his work creating an easier-to-use OO-DFT interface in Q-Chem, and how he's applied it in practical research applications.

Vibrational circular dichroism (VCD) is a key technique for distinguishing between molecular enantiomers, which is essential in areas like drug discovery. Q-Chem 6.4 provides restricted and unrestricted ab initio predictions of VCD spectra. Try today: q-chem.com/try/

Don't forget about our upcoming Q-Chem webinar from Juan E. Arias Martinez on his recent work creating a new OO-DFT (ΔSCF) interface in Q-Chem! He will also discuss how he has used the new interface to study donor-acceptor charge-transfer excitations. zoom.us/webinar/regist…

Core-level spectra reveal a lot about valence virtual orbitals, especially for open-shell systems, but current methods often suffer from spin contamination. CVS-XCIS resolves the spin contamination issue, enabling accurate calculations for these systems. youtube.com/watch?v=PN-LyN…

Q-Chem provides one of the most extensive libraries for computational #spectroscopy, including: IR, UV-Vis, and vibronic spectra; X-ray spectra; restricted and unrestricted VCD; and more. Follow along this week as we discuss the latest spectroscopy developments in Q-Chem!

Join us on April 23 at 11AM PDT for a webinar from Juan E. Arias Martinez on his new ΔSCF (OO-DFT) interface in Q-Chem! It's easier to use and includes crucial analysis tools; he will also discuss how he has used it to study charge-transfer excitations. zoom.us/webinar/regist…

Q-Chem developers published a new numerical sparsity approach to local correlation for MP2; it scales competitively with (sometimes better than!) DLPNO-MP2 and will be extended to double-hybrid #DFT in QC7, providing speedup and better accuracy. doi.org/10.1021/acs.jc…

An example of Q-Chem's #DFT in action: Authors used Q-Chem for a large benchmark study on RDB7, a large, diverse dataset containing chemical kinetics data for 11,926 reactions. Their work establishes best practices for DFT studies of reaction kinetics. doi.org/10.1039/D5CP01…

The new COACH #DFT functional (developed by Liang and Head-Gordon) provides improved transferability and accuracy over existing RSH meta-GGAs, like ωB97M-V, for a wide variety of systems. Read more: arxiv.org/pdf/2603.23466 COACH will be available in Q-Chem 7, coming June 2026!

Did you know that Q-Chem contains the first implementation of analytical second derivatives for VV10? This provides faster frequency calculations for popular #DFT functionals like B97M-V, ωB97X-V, and ωB97M-V. doi.org/10.1063/5.0152… Try Q-Chem: q-chem.com/try/