M. Rodríguez-Mayorga

Abinit 2025: New capabilities for the predictive modeling of solids and nanomaterials Abinit is a widely used scientific software package implementing density functional theory and many related functionalities for excited states and response prop

doi.org/10.1063/5.0288278 Abinit 2025: New capabilities for the predictive modeling of solids and nanomaterials. #compchem

Analytic $G_0W_0$ gradients based on a double-similarity transformation equation-of-motion coupled-cluster treatment The accurate prediction of ionization potentials (IPs) is central to understanding molecular reactivity, redox behavior, and spectroscopic properties. While vertical IPs can be accessed directly from ...

arxiv.org/abs/2510.23275 #compchem

Professor Emeritus Axel D. Becke @dalhousieu.bsky.social has passed away at age 72.

Yes

ABINIT School 2026

Learning electronic structure calculations using ABINIT

Feb. 2 - 6 2026 - Bruyères-le-Châtel, France abischool.abinit.org

Fully Analytic Nuclear Gradients for the Bethe–Salpeter Equation The Bethe–Salpeter equation (BSE) formalism, combined with the GW approximation for ionization energies and electron affinities, is emerging as an efficient and accurate method for predicting optical excitations in molecules. In this Letter, we present the first derivation and implementation of fully analytic nuclear gradients for the BSE@G0W0 method. Building on recent developments for G0W0 nuclear gradients, we derive analytic nuclear gradients for several BSE@G0W0 variants. We validate our implementation against numerical gradients and compare excited-state geometries and adiabatic excitation energies obtained from different BSE@G0W0 variants with those from state-of-the-art wave function methods.

Fully Analytic Nuclear Gradients for the Bethe–Salpeter Equation | The Journal of Physical Chemistry Letters pubs.acs.org/doi/10.1021/... #compchem

The 3e- of each Li are indistinguible and all contribute to the observed local 0.5 (spin up + spin down) probablity. They are entangled but not just n electrons.. all are if you treat the system like a FCI wavefunction. So yes, fragments should be entangled that is my guess

For H2 I think they should but for any other system you cannot really say what pair of electrons forms the bond. All participate in the bond when you think about the FCI wavefunction. Same for the cleavage, if you break H_n you get n electrons entagled, but if you break Li_n

Connections between Richardson-Gaudin States, Perfect-Pairing, and Pair Coupled-Cluster Theory Slater determinants underpin most electronic structure methods, but orbital-based approaches often struggle to describe strong correlation efficiently. Geminal-based theories, by contrast, naturally c...

arxiv.org/abs/2510.06144 Exploring the "Connections between Richardson-Gaudin States, Perfect-Pairing, and Pair Coupled-Cluster Theory." #compchem @titouloos.bsky.social @johnsontheochem.bsky.social

Using topology for understanding your computational results The integration of quantum theory (QT) into chemistry has significantly enhanced computational accuracy, yet challenges remain in translating quantum mechanical results into intuitive chemical concept...

#compchem Using topology for understanding your computational results (J. Contreras-Garcia, collaboration A. Pendas) www.degruyterbrill.com/document/doi...

Eduard Matito and Mario Piris from our lab presenting their recent work at QVEST2025 at Schloss Ringberg
@dipcehu.bsky.social
@ehu.eus

🚨Abstracts for POSTERS still accepted🚨

➡️ jtms2025.sciencesconf.org

Don't forget to complete your registration/payment before October 10th⚠️

@reseauscf.bsky.social
@sfp-physique.bsky.social
@cecamevents.bsky.social
@icmcb.bsky.social
@icgmmontpellier.bsky.social
@univbordeaux.bsky.social

A Reusable Library for Second-Order Orbital Optimization Using the Trust Region Method We present a reusable, open-source software implementation of the second-order trust region algorithm in the new OpenTrustRegion library. We apply the implementation to the general-purpose optimizatio...

New preprint online today - spearheaded by my very talented postdoc, Jonas - on a new reusable, open-source software implementation of the second-order trust region algorithm:

arxiv.org/abs/2509.13931

Here are some of the reasons why this library may be useful for a great many in our community. 👇

#chemjobs #compchem

Assistant Professorship in Theoretical Chemistry at University of Cambridge

www.ch.cam.ac.uk/job/52637

Parquet theory for molecular systems. I. Formalism and static kernel parquet approximation The $GW$ approximation has become a method of choice for predicting quasiparticle properties in solids and large molecular systems, owing to its favorable accuracy-cost balance. However, its accuracy ...

arxiv.org/abs/2509.03253 #compchem

Richardson–Gaudin states of non-zero seniority. II. Single-reference treatment of strong correlation Strongly correlated systems are well described as a configuration interaction of Slater determinants classified by their number of unpaired electrons. This trea

pubs.aip.org/aip/jcp/arti...

The call is now live. Please see this thread for further information:

bsky.app/profile/janu...

Abinit 2025: New Capabilities for the Predictive Modeling of Solids and Nanomaterials Abinit is a widely used scientific software package implementing density functional theory and many related functionalities for excited states and response properties. This paper presents the novel fe...

Interested in condensed matter? There is a new paper describing the most recent capabilities included in Abinit. Thrilled to have contributed to it 😎! arxiv.org/abs/2507.08578

Fully Analytic Nuclear Gradients for the Bethe--Salpeter Equation The Bethe-Salpeter equation (BSE) formalism, combined with the $GW$ approximation for ionization energies and electron affinities, is emerging as an efficient and accurate method for predicting optica...

arxiv.org/abs/2507.02160 #compchem

Richardson-Gaudin states of non-zero seniority II: Single-reference treatment of strong correlation Strongly correlated systems are well described as a configuration interaction of Slater determinants classified by their number of unpaired electrons. This treatment is however unfeasible. In this man...

Very short follow-up after the ridiculous part I. Short excitation-based CI of RG states converges quickly.

(ordinarily, I'd reply to a post from @titouloos.bsky.social )

arxiv.org/abs/2506.09379

#compchem Vacuum polarization in a one-dimensional effective quantum-electrodynamics model (T. Audinet, J. Toulouse, collaboration A. Levitt) iopscience.iop.org/article/10.1...

🎉 Excited to share our latest publication in Physical Review Letters:
✨Advancing Natural Orbital Functional Calculations through Deep Learning-Inspired Techniques for Large-Scale Strongly Correlated Electron Systems✨

🚀 Find the full article here:
journals.aps.org/prl/abstract...

Looking forward to meeting!

#PhDposition in Computational #Astrobiology & #QuantumChemistry! Join us at Chalmers in 🇸🇪. Collab with NASA's JPL and @starsarecalling.bsky.social in 🇺🇸. @astrobiology.bsky.social @thephdplace.bsky.social @bluemarblespace.bsky.social #chemsky #compchem
www.chalmers.se/en/about-cha...

Enhorabuena 👏👏

MOLGW version 3.4 is out! · molgw molgw · Discussion #48 What's new in version 3.4 Overview Complex wavefunctions X2C relativistic wavefunctions for HF/DFT calculations Possibility to link with LIBCINT whatever the p-orbital ordering Support for alternat...

MOLGW 3.4 is out! Want to use/test i) the G3W2 approx, ii)
complex molecular orbitals, iii) X2C relativistic wavefunctions for HF/DFT calculations, iv) use alternate compilers: LLVM flang/clang++ and Intel ifx/icx ? #compchem github.com/molgw/molgw/...

I (pre-)processed 150 submissions to Theor. Chem. Acc. during Jan-Feb. Some tips for first #compchem users:
- #DFT is by far the most used method, but it needs some benchmarking too
- Don’t describe the results, tell us a story
- Take seriously the cover letter and the list of reviewers suggested

Efficient Energy Measurement of Chemical Systems via One-Particle Reduced Density Matrix: A NOF-VQE Approach for Optimized Sampling In this work, we explore the use of the one-particle reduced density matrix (1RDM) to streamline energy measurements of chemical systems on quantum computers, particularly within the variational quantum eigensolver (VQE) framework. This approach leverages the existence of an exact energy functional of the 1RDM, enabling a reduction in both the number of expectation values to measure and the number of circuits to execute, thereby optimizing quantum resource usage. Specifically, sampling the 1RDM involves measuring only elements, which is significantly fewer than the required for the Hamiltonian’s expectation value ⟨Ĥ⟩. We demonstrate our approach by harnessing the well-established natural orbital functional (NOF) theory, using the natural orbitals and occupation numbers derived from the diagonalization of the 1RDM measured from the quantum computer. Starting with the H2 system, we validate the accuracy of our method by comparing the energy derived from NOF approximations applied to the exact wave function with the value obtained from ⟨Ĥ⟩. This is followed by an optimization of the gate parameters by minimizing the energy using the NOF approximations as the objective function. The analysis is extended to larger systems, such as LiH, Li2, OH–, FH, NeH+, and F2 using a wave function ansatz with single and double excitation gates. This NOF-based method reduces the scaling cost of circuit executions compared to standard VQE implementations, achieving around 90% savings in the systems used in this work. Overall, by using a well-performing NOF as the objective function, the proposed NOF-VQE demonstrates the viability of NOF approximations for obtaining accurate energies in the noisy intermediate-scale quantum era and underscores the potential for developing new functionals tailored to quantum computing applications.

✨ Excited to share our new paper: "Efficient Energy Measurement of Chemical Systems via One-Particle Reduced Density Matrix: A NOF-VQE Approach for Optimized Sampling" by Felipe Lew-Yee and Mario Piris

⚛️ Read the full paper here: pubs.acs.org/doi/10.1021/...

Less than two weeks left to register for the 2025 CECAM Flagship school in computational photochemistry: shorturl.at/xsbEa with lectures from Basile Curchod, Javier Segarra, Javier Cerezo, Roger Bello and myself. Please spread the word!
#compchem #compchemsky

‘My boss was crying.’ NSF confronts potentially massive layoffs and budget cuts Trump could propose slashing agency’s budget by two-thirds

The #EU should dedicate substantial resources to attracting American top reseach talent, asap. Then double research funding, collectively and nationally. It’s time to pick up the ball. www.science.org/content/arti...