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FACCTs is bringing the ORCA quantum chemistry software to industry - promoting the next Quantum leaps in the Pharma, Materials and Chemical Industries.

Visit us at www.faccts.de
Pinned
Most people know us for our contributions to ORCA — but have you heard of WEASEL?

WEASEL is our smart workflow driver that delivers efficient workflows for complex quantum chemical processes.

Learn more about WEASEL at www.faccts.de/weasel

youtu.be/stYgkMZwi5s

#WEASEL #FACCTs #CompChem #ChemSky
WEASEL
YouTube video by FACCTs
youtu.be
Reposted by FACCTs
New paper with my colleagues at #UFRRJ and #UFRGS. In this work #ORCA nailed to show in extreme detail the formation process of a zinc complex AND the charge transfer. Yes, we have AIMD, we have DLPNO-CCSD(T) and a little bit of TD-DFT.

#CompChem #ChemSky

doi.org/10.1016/j.dy...
November 11, 2025 at 11:14 AM
Reposted by FACCTs
Finally our paper on copper corroles is out in Inorganic Chemistry @pubs.acs.org!

#chemsky #realtimechem #science #comp_chem
1/n

Electronic Structure and Hypercorrole Features of Deprotonated Free-Base and Reduced Copper Corroles | Inorganic Chemistry pubs.acs.org/doi/10.1021/...
Electronic Structure and Hypercorrole Features of Deprotonated Free-Base and Reduced Copper Corroles
We report the synthesis, crystal structure, and spectroscopic and computational electronic-structural characterization of two copper corroles, [Cu(5,15-bis(4-methylcarboxyphenyl)-10-(2-methylcarboxyphenyl)corrole)] (1Cu) and [Cu(5,15-bis(4-nitrophenyl)-10-(2-methylcarboxyphenyl)corrole)] (2Cu), as well as spectroscopic and computational studies on the corrole ligands (H3L1 and H3L2) in their neutral and anionic forms. We have found that the anionic corroles containing the 4-nitrophenyl substituents in positions 5 and 15 of the corrole ring show hypercorrole behavior, where the Q-bands are considerably more intense and red-shifted compared to those in the 4-methylcarboxyphenyl-substituted corroles. Electronic structure calculations using wave function methods (CASSCF/NEVPT2) reveal that the intense Q-bands, which extend slightly into the NIR region, are charge-transfer bands from the anionic corrole core to the strongly electron-withdrawing 4-nitrophenyl substituents. We further show that 2Cu can be reduced indirectly in the presence of excess F– or OH–, and the Q-band shifts toward the red in the polar environment containing the corresponding salts. Our study provides examples of easy-to-prepare anionic corroles, metalated and unmetalated, that show hypercorrole behavior and NIR absorption, and thus could find use in hyperthermal processes.
pubs.acs.org
November 7, 2025 at 11:54 AM
We will be presenting at the World Science Day in Bochum, organized by RESOLV! We look forward to seeing many of you at this fantastic science and industry networking event.

www.solvation.de/news/resolv-...

#FACCTs #RESOLV #WorldScienceDay25 #ScienceMeetsIndustry #Innovation
November 5, 2025 at 10:52 AM
Most people know us for our contributions to ORCA — but have you heard of WEASEL?

WEASEL is our smart workflow driver that delivers efficient workflows for complex quantum chemical processes.

Learn more about WEASEL at www.faccts.de/weasel

youtu.be/stYgkMZwi5s

#WEASEL #FACCTs #CompChem #ChemSky
WEASEL
YouTube video by FACCTs
youtu.be
October 27, 2025 at 1:45 PM
Reposted by FACCTs
GDCh wrote a section about our work! Solvent and system specific radii for CPCM with consistent analytic gradients.

Check out the GDCh article (doi.org/10.1002/nadc...) or our work (doi.org/10.1002/jcc....)!

#compchem #quantumchemistry
Notizen aus der Forschung
Click on the article title to read more.
doi.org
September 1, 2025 at 8:19 AM
Visit Anneke Dittmer, Bernardo de Souza, and Christoph Riplinger at the SMASH in beautiful Porto! Get the latest information about our quantum chemical NMR toolkit. We look forward to seeing you there!

#FACCTs #ORCAqc #SMASH2025 #CompChem #TheoChem #NMR
September 22, 2025 at 9:06 AM
We are visiting STC in Berlin! Come and join us at our poster presentation—we look forward to many exciting discussions with you! Also check out all the new ORCA features and the new ORCA Python interface, OPI!

#FACCTs #ORCAqc #STC2025 #CompChem #TheoChem
September 22, 2025 at 9:01 AM
Reposted by FACCTs
I have an open PhD position. The exact topic is negotiable and can range from implementing new quantum-chemical methods in @orca-qc-official.bsky.social to computational studies of open-shell molecules.
🔗 Details: www.langresearch.org/open-phd-fel...

Please share!

#PhDposition #CompChem
Open PhD Fellowship in Quantum Chemistry at TU Berlin – Lang Research Group
www.langresearch.org
September 18, 2025 at 11:45 AM
Reposted by FACCTs
We've got a new release 1.101, which should particularly fix some bugs with Windows and Mac, and of course a variety of new features.

Highlights include support for constraints for geometry optimizations, tweaking bond lengths when changing elements, and more...

discuss.avogadro.cc/t/avogadro-1...
September 15, 2025 at 8:46 PM
We are excited to be at EuChemS CompChem, Naples!
Join our team to learn more about ORCA and its new Python interface, OPI. Don’t miss Christoph Riplinger’s talk on Tuesday at 15:45.
We’re looking forward to discussing great science with many of you!

#ORCAqc #ORCA #CompChem #QuantumChem #ChemSky
September 15, 2025 at 8:24 AM
Check out the latest release of QCxMS2 by @jogorges.bsky.social (@grimmelab.bsky.social) introducing CID. Thank you, Johannes, for interfacing it with ORCA as a QM engine!

#ORCAqc #ORCA6 #massspectrometry #CID #CompChem #ChemSky #CompChemSky
QCxMS2 can now also simulate CID mass spectra.

Just published in #JASMS : doi.org/10.1021/jasms.5c00234

Grateful to my coauthors Stefan Grimme @grimmelab.bsky.social & Marianne Engeser @unibonn.bsky.social - this is the last project of my PhD and completes my work on QCxMS2!

#MassSpec #compchem
Evaluation of the QCxMS2 Method for the Calculation of Collision-Induced Dissociation Spectra via Automated Reaction Network Exploration
Collision-induced dissociation mass spectrometry (CID-MS) is an important tool in analytical chemistry for the structural elucidation of unknown compounds. The theoretical prediction of the CID spectra plays a critical role in supporting and accelerating this process. To this end, we adapt the recently developed QCxMS2 program originally designed for the calculation of electron ionization (EI) spectra to enable the computation of CID-MS. To account for the fragmentation conditions characteristic of CID within the automated reaction network discovery approach of QCxMS2 we adapted the internal energy distribution to match the experimental conditions. This distribution can be adjusted via a single parameter to approximate various activation settings, thereby eliminating the need for explicit simulations of the collisional process. We evaluate our approach on a test set of 13 organic molecules with diverse functional groups, compiled specifically for this study. All reference spectra were recorded consistently under the same measurement conditions, including both CID and higher-energy collisional dissociation (HCD) modes. Overall, QCxMS2 achieves a good average entropy similarity score (ESS) of 0.687 for the HCD spectra and 0.773 for the CID spectra. The direct comparison to experimental data demonstrates that the QCxMS2 approach, even without explicit modeling of collisions, is generally capable of computing both CID and HCD spectra with reasonable accuracy and robustness. This highlights its potential as a valuable tool for integration into structure elucidation workflows in analytical mass spectrometry.
doi.org
September 9, 2025 at 11:53 AM
Reposted by FACCTs
🚀 JCIM: "Chemical Space Exploration with Artificial Mindless Molecules"

We present MindlessGen, an open-source tool for generating chemically diverse "mindless" molecules, and the MB2061 benchmark set with high-level reference data to test methods on unconventional systems.

doi.org/10.1021/acs....
Chemical Space Exploration with Artificial “Mindless” Molecules
We introduce MindlessGen, a Python-based generator for creating chemically diverse, “mindless” molecules through random atomic placement and subsequent geometry optimization. Using this framework, we ...
doi.org
September 3, 2025 at 11:01 AM
Great to see many of our collaborators and friends from the ORCA community including Michael Römelt, Dimitrios Pantazis, @podewitzlab.bsky.social, @letigonzalez.bsky.social, @kulikgroup.bsky.social, and many more at the QBIC VII in Berlin, Germany!

#QBICVII #CompChemSky #ChemSky #ORCAqc #ORCA
August 27, 2025 at 8:46 AM
Hot off the press: “A Two-Level Preconditioner for the CASSCF Linear-Response Equations” by our scientific advisor Benjamin Helmich-Paris (@orca-qc-official.bsky.social). Its already part of ORCA 6.1, check it out!

doi.org/10.1021/acs....

#ORCA #ORCAqc #CompChem #QuantumChem #TheoChem #CASSCF
A Two-Level Preconditioner for the CASSCF Linear-Response Equations
We present an efficient two-level strategy to accelerate the solution of the CASSCF linear-response eigenvalue problem using a customized Davidson algorithm. By identifying a subset of important response-vector components─the so-called P space─we compute and diagonalize full Hessian and metric matrix elements while treating the remaining Q-space components with a diagonal approximation. This approach decouples the orbital and configuration responses, enabling independent preconditioning of each component. Computational cost is further reduced through the resolution-of-the-identity approximation. We demonstrate significant performance gains across a diverse set of molecules, achieving speedups of up to 2.05 compared to the standard diagonal preconditioning. The largest efficiency gains are observed for MCTDA calculations involving many excited states and relatively small response-vector lengths. The two-level strategy is available in ORCA 6.1 and paves the way for extensions to dynamic polarizabilities, which require solving large-scale linear equations, as well as to time-dependent density functional theory and CI singles.
doi.org
August 25, 2025 at 9:20 AM
Check out the recent paper by List, Neese et al. that ones more demonstrates the synergy of experiment and quantum chemistry powered by ORCA (DFT, GOAT, ...) @faccts.de @orca-qc-official.bsky.social

doi.org/10.1021/jacs...

ORCA: www.faccts.de/orca/

#ORCAqc #ORCA #Catalysis #CompChem #QuantumChem
Pericyclic Umpolung in a Catalytic Asymmetric Diels–Alder Reaction of Tropone with Enol Ethers
One remarkable feature of catalysis in chemical synthesis is its capacity to override substrate-imposed reactivity and selectivity. The inversion of normal reaction patterns, commonly known as Umpolun...
doi.org
August 19, 2025 at 11:18 AM
Reposted by FACCTs
Happy to share my first PhD contribution from the @grimmelab.bsky.social! 🎓 We explored the N-H bond thermochemistry of an amine-rich cyclopentadienyl ligand motif that shows no change in N-H bond acidity when coordinated to iron - surprising!
#compchem #PCET #catalysis #ORCA
doi.org/10.1021/acso...
Expanding the PCET Thermochemistry of CpN3: N–H Bond Strengths of Metal-Free CpN3 Molecules and the Influence of Fe(CO)3 Coordination
Amine rich cyclopentadienyl (CpN3) ligands are electronically distinct from classical Cp ligand architectures, as they exhibit fascinating proton-coupled electron transfer (PCET) chemistry under acidi...
doi.org
August 7, 2025 at 7:00 PM
Reposted by FACCTs
Most of MLIPs dont distinguish between spin states, making them unsuitable for open-shell chemistry. We present AIMNet2-NSE (Neural Spin-charge Equilibration), MLIP that incorporates spin-charge equilibration for systems with arbitrary charge and spin. #compchem #skychem
chemrxiv.org/engage/chemr...
August 4, 2025 at 4:47 PM
Check out the recent paper on Excited-state methods based on state-averaged long-range CASSCF short-range DFT by Benjamin Helmich-Paris et al. And how to use it in ORCA 6.1.

doi.org/10.1039/D5CP...

www.faccts.de/docs/orca/6....

#ORCAqc #CompChem #QuantumChem #ChemSky #DFT
Excited-state methods based on state-averaged long-range CASSCF short-range DFT
In the present work we propose two distinct state-averaging (SA)-based methodologies for the calculation of excited states, in conjunction with the long-range complete active space self-consistent fie...
doi.org
August 4, 2025 at 1:36 PM
Check out our most recent collaboration on atomic polarizabilities calculated with ORCA and how they can be used to improve openCOSMO-RS.

doi.org/10.1016/j.ce...

Calculation of atomic polarizabilities with ORCA 6.1:

www.faccts.de/docs/orca/6....

#ORCAqc #Solvation #CompChem #openCOSMORS
Redirecting
doi.org
July 28, 2025 at 9:58 AM
Reposted by FACCTs
In this week’s #JournalClub @jeanquertinmont.bsky.social discusses resolution of identity / density fitting approaches #compchem with a special focus on @orca-qc-official.bsky.social www.grynova-ccc.org/journal-club...
July 4, 2025 at 8:10 AM
You can now use g-xTB @grimmelab.bsky.social with ORCA via the ExtOpt feature! Check out our new tutorial and learn how to use it in GOAT, NEB-TS and more.

www.faccts.de/docs/orca/6....

#ORCAqc #FACCTs #gxTB #CompChem #QuantumChem
ORCA as External Optimizer - ORCA 6.1 TUTORIALS
www.faccts.de
June 26, 2025 at 8:32 AM
Reposted by FACCTs
I am excited to share our latest work on the implementation of magnetic properties for large active space selected CI wavefunctions in @orca-qc-official.bsky.social. Try it out in the new ORCA 6.1!

🔗: pubs.acs.org/doi/10.1021/...

#ORCA #CompChem #QC
Treating Spin–Orbit Coupling and Spin–Spin Coupling in the Framework of the Iterative Configuration Expansion Selected CI
Spin-adapted configuration state functions (CSFs) provide a compact many-electron basis for open-shell molecules. This basis is employed in one flavor of the recently introduced iterative configuratio...
pubs.acs.org
June 24, 2025 at 7:58 AM
Reposted by FACCTs
After almost 3 years of development with @grimmelab.bsky.social, a first preliminary version of our next-generation general extended Tight-Binding (g-xTB) is now on ChemRxiv!
Catch the details at #WATOC: my talk (Thu Session B1) and Stefan’s talk (Thu Session A2).
#compchem

doi.org/10.26434/che...
g-xTB: A General-Purpose Extended Tight-Binding Electronic Structure Method For the Elements H to Lr (Z=1–103)
We present g-xTB, a next-generation semi-empirical electronic structure method derived from tight-binding (TB) approximations to Kohn–Sham density functional theory (KS-DFT). Designed to bridge the ga...
doi.org
June 24, 2025 at 7:25 AM
Create input and parse output of ORCA with the new ORCA Python Interface (OPI), an open source project supported by FACCTs. Check it out and become part of the OPI community!

GitHub: github.com/faccts/opi
Docs: www.faccts.de/docs/opi/1.0...

#ORCAqc #Python #FACCTs #CompChem #QuantumChem
GitHub - faccts/opi: ORCA Python Interface
ORCA Python Interface. Contribute to faccts/opi development by creating an account on GitHub.
github.com
June 23, 2025 at 12:14 PM
Reposted by FACCTs
The well-deserved WATOC medal was given to Frank Neese. #watoc2025 @orca-qc-official.bsky.social @faccts.de
June 22, 2025 at 4:41 PM