Q-Chem
@qchemsoftware.bsky.social
Q-Chem provides a comprehensive ab initio quantum chemistry program, allowing scientists worldwide to model chemical problems quickly and accurately. http://q-chem.com/
Did you miss Tuesday's webinar from Martin Head-Gordon on the latest developments in Q-Chem 7? Don't worry, we've got you covered—the recording is now available on our YouTube channel: youtu.be/5U7TDNGcpFU Request a free trial of Q-Chem 7 today: q-chem.com/try/
SAPT vs. EDA: How do they compare, and could they find some common ground? Check out this new preprint for a side-by-side comparison of Q-Chem’s two popular energy decomposition analysis schemes: doi.org/10.26434/che... Try SAPT+MBD and ALMO-EDA in QC7: q-chem.com/try/
Our upcoming Q-Chem 7 webinar has been rescheduled for July 28th! Join us as Prof. Martin Head-Gordon reviews some of the latest and greatest features in Q-Chem 7. Register here: zoom.us/webinar/regi... We hope to see you there!
Join us next week (July 21) for a webinar on the new features available in Q-Chem 7, our latest generational software release! Register today: zoom.us/webinar/regi...
New in Q-Chem 7: New CAP-DFT functionals! CAP-DFT, recently extended to GGA and derived hybrids, allows researchers to model energies and lifetimes of metastable molecular anions at an accuracy that rivals EOM-CC! doi.org/10.1021/acs.... Try Q-Chem 7: q-chem.com/try/
Q-Chem 7 is here! Read about the latest features, including new DFT functionals, numerical sparsity speedups, faster NMR, MRSF-TDDF, and more: q-chem.com/explore/qc7/ Request a free, month-long demo of Q-Chem and QC-PBC, free of charge: q-chem.com/try/ #compchem
Last year, researchers developed regularized second-order perturbative (PT2) methods in QC-PBC for modeling solids. BW-s2 in particular provides accurate results for metals, semiconductors, and molecular crystals, and will be available in Q-Chem 7! pubs.acs.org/doi/10.1021/...
One of the things we're most excited about in Q-Chem 7 is QC-PBC: A new module that uses a GTO basis for modeling periodic systems. Highlights include fast hybrid DFT; CC and MP2; analytic derivatives; excited states; solvation; and EDA. Pre-order today: q-chem.com/purchase/
New in Q-Chem 7: Faster CC2 and CCSD with THC-sRI! Q-Chem developers recently combined their existing sRI framework in Q-Chem with tensor hypercontraction (THC) to provide accurate energy derivatives. arxiv.org/html/2509.06... Preorder Q-Chem 7: q-chem.com/purchase/
Q-Chem 7 includes many improvements to CC2: * Large speedups for RI-CC2 ground state * CC2 and RI-CC2 Dyson orbitals for EA, IP, EE-EA, and EE-IP * RI-CC2 and sRI-CC2 oscillator strengths (read their paper: arxiv.org/html/2509.06...) Pre-order Q-Chem 7! q-chem.com/purchase/
Q-Chem offers state-of-the-art tools for handling electron correlation, such as MP2 and CC methods; the Q-Chem 6 generation has included new correlated methods like EOM-CCSDT, BW-s2, TDDFT/TDA-SOC, and MRSF-TDDFT. Stay tuned as we highlight recent and upcoming features!
Researchers recently probed the origins of homochirality in biological systems and found that electron spin may be the key. Their conclusions are supported by EOM-EA-CCSD and Breit-Pauli SOC calculations in Q-Chem. iopenshell.usc.edu/pubs/pdf/sci... Try Q-Chem: q-chem.com/try/
New in Q-Chem 7: Excited-state analysis based on Earth Mover's Distance (EMD)! This provides a new quantitative metric for characterizing charge-transfer in excitations. Read the paper from the developers: doi.org/10.1021/acs.... Pre-order Q-Chem 7: q-chem.com/purchase/
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/10.1063/5.00...
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.... 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).
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....
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-L...
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/regi...
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....
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/D5CP...
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!
As any computational chemist who uses #DFT knows, converging SCF can be tricky. Q-Chem's “Robust SCF” algorithm provides a black-box approach that automatically detects common convergence issues and makes the appropriate corrections. Read more here: manual.q-chem.com/6.4/sub_scf_...
In this recent paper, authors use Q-Chem's DFT alongside experiment to show that metal ions can be used as EWGs and establish a quantitative foundation for Hammett-like parameters for metal ions. doi.org/10.1021/acs.... Try Q-Chem: q-chem.com/try/
We just published a paper detailing our quantum–classical simulation package QC Lab in JCTC @acs.org! This marks the release of version 1.1.1, featuring a basic interface with @qchemsoftware.bsky.social for TD-DFT calculations. @nuchemistry.bsky.social pubs.acs.org/doi/10.1021/...
QC Lab: A Python Package for Quantum–Classical Dynamics
QC Lab is an open-source Python package for quantum–classical (QC) dynamics simulations aimed to promote the development of QC algorithms, and their application to a wide variety of relevant model problems. It follows a modular design that facilitates cross-compatibility between algorithms and models. By decomposing algorithms and models into a series of tasks and ingredients that can be substituted and reused, it minimizes development efforts and code redundancy. In this Paper, we introduce the first stable version of QC Lab, and describe its design philosophy.
pubs.acs.org
Join us on 3/26 for our a Q-Chem webinar from Anthuan Pérez (Universität des Saarlandes)! He will be discussing his recent work with projection-based CC-in-DFT methods in Q-Chem, which he uses to model static polarizabilities of solvated organic molecules. zoom.us/webinar/regi...
Check out the latest paper from Q-Chem developers at KU Leuven, in which they present a new method for computing partial Auger decay widths faster and more robustly! doi.org/10.1021/acs.... Follow us to stay up-to-date on new features and papers from Q-Chem developers!
Computation of Partial Auger Decay Widths from Complex-Valued Equation-of-Motion Coupled-Cluster Energies
We discuss the computation of partial Auger decay widths with equation-of-motion ionization-potential coupled-cluster (EOMIP-CCSD) theory in the framework of non-Hermitian quantum mechanics (NHQM). In NHQM, the decaying character of metastable states is described with complex energies and the total decay width is obtained directly from the total energy. In contrast, the computation of partial decay widths, i.e., the contributions of different decay channels to the total width, requires further analysis. However, partial widths are important for Auger spectroscopy as they determine the probability with which different final states are formed and hence the shape of the Auger spectrum. Recently, we introduced Auger channel projectors (ACPs), which selectively remove decay channels from the EOMIP-CCSD excitation manifold. This method requires a separate EOMIP-CCSD calculation for each decay channel. Here, we suggest an alternative: We solve the EOMIP-CCSD equations for the core-ionized state in the full excitation manifold and decompose the imaginary part of the resulting energy. In this way, we obtain all partial decay widths at once. We compute Auger spectra for K-edge-ionized states of methane, ethane, and hydrogen sulfide, and a Coster–Kronig spectrum for L1-edge-ionized hydrogen sulfide. The results obtained with our new approach differ only negligibly from ACP results. We also present the first Auger spectra for the cyanide anion, including vibrational broadening, and discuss the differences between the spectra of the carbon core hole and the nitrogen core hole.
doi.org
Congratulations to researchers at CSU Fullerton on their recent paper! They develop descriptors for photoacidity and photobasicity; they use several Q-Chem capabilities (including DFT and libwfa) in their work. doi.org/10.1021/acs.... Try Q-Chem today: q-chem.com/try/
