Two teams, one quest: democratizing quantum chemistry. We’re very happy to support the fantastic team at @thematterlab.bsky.social and to see this great achievement. Many thanks as well for trusting the ORCA quantum chemistry package!

#ORCAqc #QuantumChem #AgenticAI #ElAgente

Redoxpotentials with ORCA and OPI

Check out the new Jupyter notebook on the calculation of redox potentials with #ORCA and #OPI by #FACCTs Computational Scientist Hagen Neugebauer:

www.faccts.de/docs/opi/nig...

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

#ORCAqc #ORCAPI #CompChem #Python #ChemSky

The photohydrolysis of furans The defossilization of the chemical industry is accelerated by the shift from petroleum- to biomass-based feedstocks. At the center stage are bioderived furans, from which valuable platform chemicals ...

Check out the recent work on the photohydrolysis of furans by List et al., with contributions from Benjamin Helmich-Paris. For a quick start on GOAT, DLPNO-CCSD(T), and more also check our ORCA tutorials www.faccts.de/docs/orca/tu....

doi.org/10.1126/scie...

#MPIKOFO #FACCTs #CompChem #ORCAqc

FACCTs at the JCF FJS 2026

Young, curious scientists are our future. That’s why we’re especially delighted to sponsor this year’s #JCF Frühjahrssymposium in our hometown of Cologne. We’re looking forward to meeting many of you there!

symposium.jcf.io

#FACCTs #FJS2026 #JungesChemieForum #GDCh #ORCAqc #OPI #ChemSky

FACCTs at the CCSC 2026

We’re excited to sponsor this year’s #CCSC2026.

Meet us in Munich to learn more about the latest ORCA features and our ORCA Python Interface #OPI. We’re looking forward to seeing you there!

CCSC: ccsc2026.github.io
ORCA: www.faccts.de/orca/
OPI: github.com/faccts/opi

#FACCTs #ORCAqc #CompChem #ML

Great to see applications of #ORCA's External Optimizer feature! Let us know which methods you'd like to use with it in the future.

Check out our tutorials on ExtOpt: www.faccts.de/docs/orca/6....

#ORCAqc #CompChem #ExtOpt

100000 registered ORCA users!

What an incredible Christmas gift!

The #ORCA community has reached a major milestone: 100,000 registered users.
Thank you all for your trust and for being such an important part of ORCA’s journey. Your support is what makes this success possible.

#ORCAqc #FACCTs #MPIKOFO #CompChem #ChemSky

Happy Holidays!

We at FACCTs wish you all a wonderful and peaceful holiday season and a great start to the new year!

#FACCTs #ORCAqc #WEASEL #Holidays

Ligand Field Tuning of Photoreactivity: Contrasting Low‐Spin and High‐Spin Fe(III)‐Azido Complexes Why do near-identical Fe(III)-azido complexes exhibit different photoreactivity profiles? Linking spin states and key normal modes to wavelength-dependent photoreductive and photooxidative reaction p...

#CASSCF and (TD-)DFT are well-established components of #ORCA's method portfolio. Check out the new paper by Krewald et al., who use both for tuning the photoreactivity of Fe(III)-azido complexes.

doi.org/10.1002/cptc...

CASSCF in ORCA: www.faccts.de/docs/orca/6....

#ORCAqc #CompChem #QuantumChem

ORCA is brought to you by @faccts.de and @orca-qc-official.bsky.social

#compchem #ORCAqc #FACCTs

FACCTs at the SMASH 2025

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

FACCTs at the STC 2025

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

FACCTs at EuChemS CompChem 2025

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

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

QBIC VII in Berlin sponsored by FACCTs

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

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.

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

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...

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

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...

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

Redirecting

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

ORCA as External Optimizer - ORCA 6.1 TUTORIALS

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

GitHub - faccts/opi: ORCA Python Interface ORCA Python Interface. Contribute to faccts/opi development by creating an account on GitHub.

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

FACCTs at the WATOC 2025

We are visiting the WATOC 2025, Oslo! Come and visit our booth to discuss and join Christoph Riplingers talk on

Tuesday, 18:30 - Deciphering Ligand Interactions with Biomolecules Using Quantum Mechanical Methods

Hope to see you there!

#FACCTs #WATOC2025 #CompChemSky #ChemSky #ORCAqc #ORCA61

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

Missed the ORCA 6.1 release event? All talks are now online on our YouTube channel!

www.youtube.com/@faccts_orca

ORCA 6.1 Release Event Playlist:

www.youtube.com/watch?v=mRSk...

#ORCA61 #ORCAqc #FACCTs #MPIKOFO #CompChem #QuantumChem #ChemSky #CompChemSky

Join our Cloud HD Video Meeting Zoom is the leader in modern enterprise cloud communications.

The ORCA 6.1 online release event starts soon (12:00 CET), we hope to see you there!

ZOOM Webinar: eu02web.zoom-x.de/j/6815327020...

Passcode: 297206

#ORCA61 #ORCAqc #CompChem #QuantumChem #TheoChem #ChemSky #CompChemSky #FACCTs #MPIKOFO

New methods in ORCA 6.1. Bubblepoles, MCPDFT, ADFT, NEVPT3, NEVPT4(SD)

ORCA 6.1 will be released tomorrow after the online event to which you are all invited! As a final appetiser, we have a sneak preview of some new methods that will be available in the new version.

#ORCA61 #ORCAqc #CompChem #QuantumChem #TheoChem #FACCTs #MPIKOFO #ChemSky #CompChemSky

ORCA 6.1 Release Event Link Available

Join us for the ORCA 6.1 online release event!

ZOOM Webinar

ORCA 6.1 Release Event - Jun 17, 2025 12:00 AM Amsterdam, Berlin, Rome, Stockholm, Vienna (CEST)

Link: eu02web.zoom-x.de/j/6815327020...

Passcode: 297206

#ORCA61 #ORCAqc #FACCTs #CompChem #QuantumChem #ChemSky #CompChemSky

ORCA 6.1 Features. Multiscale and large molecule simulations.

New week, new ORCA 6.1 features (@faccts.de & @orca-qc-official.bsky.social )! Today we preview some improvements for multiscale- and large molecule simulations as well as some new properties and utilities. Stay tuned!

#ORCA61 #ORCAqc #FACCTs #QuantumChem #CompChem #ChemSky #CompChemSky

ORCA 6.1 release event on June 17th 2025. Online ZOOM webinar.

Save the Date! Join us for the ORCA 6.1 (@faccts.de & @orca-qc-official.bsky.social) online release event on 17th June 2025 12:00 CEST. We look forward to many exciting discussions with you!

#ORCAqc #ORCA61 #FACCTs #QuantumChem #CompChem #ChemSky #CompChemSky

FACCTs at the ICCS2025

@faccts.de will be exhibiting at ICCS2025 (@intconfchemstr.social.edu.nl.ap.brid.gy)! We’re looking forward to meeting you all at booth 9 and invite you to attend Christoph Riplingers and Bernardo de Souza's (@bernadsz.bsky.social) talks.

#FACCTs #ORCAqc #ICCS2025 #ChemSky #CompChemSky #QuantumChem

New energy decomposition methods coming with ORCA 6.1

ORCA 6.1 (@faccts.de & @orca-qc-official.bsky.social) will feature various new energy decomposition methods developed by the Bistoni lab. ADLD is one of them, check out the paper doi.org/10.1021/acsc....

#ORCA61 #ORCAqc #CompChem #QuantumChem #ChemSky #CompChemSky