Andreas Savin
YOU?
Author Swipe
View article: Long-Range Configuration Interaction with an <i>Ab Initio</i> Short-Range Correction and an Asymptotic Lower Bound
Long-Range Configuration Interaction with an <i>Ab Initio</i> Short-Range Correction and an Asymptotic Lower Bound Open
Short-range corrections to long-range selected configuration interaction calculations are derived from perturbation theory considerations and applied to harmonium (with two to six electrons for some low-lying states). No fitting to referen…
View article: Modified Expression for the Hamiltonian Expectation Value Exploiting the Short-Range Behavior of the Wave Function
Modified Expression for the Hamiltonian Expectation Value Exploiting the Short-Range Behavior of the Wave Function Open
The expectation value of the Hamiltonian using a model wave function is widely used to estimate the eigenvalues of electronic Hamiltonians. We explore here a modified formula for models based on a long-range interaction. It scales differen…
View article: Exploring the role of mean‐field potentials and short‐range wave function behavior in the adiabatic connection
Exploring the role of mean‐field potentials and short‐range wave function behavior in the adiabatic connection Open
In this article, we explore the construction of Hamiltonians with long‐range interactions and their corrections using the short‐range behavior of the wave function. A key aspect of our investigation is the examination of the one‐particle p…
View article: Second-order adiabatic connection: The theory and application to two electrons in a parabolic confinement
Second-order adiabatic connection: The theory and application to two electrons in a parabolic confinement Open
The adiabatic connection formalism, usually based on the first-order perturbation theory, has been generalized to an arbitrary order. The generalization stems from the observation that the formalism can be derived from a properly arranged …
View article: FLEIM: A stable, accurate and robust extrapolation method at infinity for computing the ground state of electronic Hamiltonians
FLEIM: A stable, accurate and robust extrapolation method at infinity for computing the ground state of electronic Hamiltonians Open
The Kohn-Sham method uses a single model system, and corrects it by a density functional the exact user friendly expression of which is not known and is replaced by an approximated, usable, model. We propose to use instead more than one mo…
View article: Correcting Models with Long-Range Electron Interaction Using Generalized Cusp Conditions
Correcting Models with Long-Range Electron Interaction Using Generalized Cusp Conditions Open
Sources of energy errors resulting from the replacement of the physical Coulomb interaction by its long-range erfc(μr)/r approximation are explored. It is demonstrated that the results can be dramatically improved and the range of μ giving…
View article: The effect of uncertainty on building blocks in molecules
The effect of uncertainty on building blocks in molecules Open
International audience
View article: The effect of uncertainty on building blocks in molecules
The effect of uncertainty on building blocks in molecules Open
Probabilities to find a chosen number of electrons in flexible domains of space are calculated for highly correlated wave functions. Quantum mechanics can produce higher probabilities for chemically relevant arrangements of electrons in th…
View article: What is the number of electrons in a spatial domain?
What is the number of electrons in a spatial domain? Open
We like to attribute a number of electrons to spatial domains (atoms, bonds, ...). However, as a rule, the number of electrons in a spatial domain is not a sharp number. We thus study probabilities for having any number of electrons (betwe…
View article: Should We Gain Confidence from the Similarity of Results between Methods?
Should We Gain Confidence from the Similarity of Results between Methods? Open
Confirming the result of a calculation by a calculation with a different method is often seen as a validity check. However, when the methods considered are all subject to the same (systematic) errors, this practice fails. Using a statistic…
View article: DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science
DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science Open
In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practiti…
View article: Was Pauling Mistaken about Metals?
Was Pauling Mistaken about Metals? Open
Pauling described metallic bonds using resonance. The maximum probability domains in the Kronig–Penney model can show a picture of it. When the walls are opaque (and the band gap is large) the maximum probability domain for an electron pai…
View article: On connecting density functional approximations to theory
On connecting density functional approximations to theory Open
Usually, density functional models are considered approximations to density functional theory, However, there is no systematic connection between the two, and this can make us doubt about a linkage. This attitude can be further enforced by…
View article: Models and corrections: Range separation for electronic interaction—Lessons from density functional theory
Models and corrections: Range separation for electronic interaction—Lessons from density functional theory Open
Model Hamiltonians with long-range interaction yield energies are corrected taking into account the universal behavior of the electron–electron interaction at a short range. Although the intention of this paper is to explore the foundation…
View article: Erratum: Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. I. Theory [J. Chem. Phys. 152, 164108 (2020)]
Erratum: Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. I. Theory [J. Chem. Phys. 152, 164108 (2020)] Open
First Page
View article: Impact of non-normal error distributions on the benchmarking and ranking of quantum machine learning models
Impact of non-normal error distributions on the benchmarking and ranking of quantum machine learning models Open
Quantum machine learning models have been gaining significant traction within atomistic simulation communities. Conventionally, relative model performances are being assessed and compared using learning curves (prediction error vs. trainin…
View article: Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. I. Theory
Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. I. Theory Open
The comparison of benchmark error sets is an essential tool for the evaluation of theories in computational chemistry. The standard ranking of methods by their mean unsigned error is unsatisfactory for several reasons linked to the non-nor…
View article: Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. II. Applications
Probabilistic performance estimators for computational chemistry methods: Systematic improvement probability and ranking probability matrix. II. Applications Open
In Paper I [P. Pernot and A. Savin, J. Chem. Phys. 152, 164108 (2020)], we introduced the systematic improvement probability as a tool to assess the level of improvement on absolute errors to be expected when switching between two computat…
View article: Acknowledging User Requirements for Accuracy in Computational Chemistry Benchmarks
Acknowledging User Requirements for Accuracy in Computational Chemistry Benchmarks Open
Computational chemistry has become an important complement to experimental measurements. In order to choose among the multitude of the existing approximations, it is common to use benchmark data sets, and to issue recommendations based on …
View article: Acknowledging user requirements for accuracy in computational chemistry benchmarks
Acknowledging user requirements for accuracy in computational chemistry benchmarks Open
Computational chemistry has become an important complement to experimental measurements. In order to choose among the multitude of the existing approximations, it is common to use benchmark data sets, and to issue recommendations based on …
View article: Strong correlation in density functional theory: general discussion
Strong correlation in density functional theory: general discussion Open
International audience
View article: New density-functional approximations and beyond: general discussion
New density-functional approximations and beyond: general discussion Open
Nikitas Gidopoulos opened a discussion of the introductory lecture by Weitao Yang: Hello Prof. Yang and thank you for your very insightful lecture! My question is: Let's take a density functional approximation where the xc energy is an exp…
View article: Erratum: “Probabilistic performance estimators for computational chemistry methods: The empirical cumulative distribution function of absolute errors” [J. Chem. Phys. 148, 241707 (2018)]
Erratum: “Probabilistic performance estimators for computational chemistry methods: The empirical cumulative distribution function of absolute errors” [J. Chem. Phys. 148, 241707 (2018)] Open
First Page
View article: Smooth models for the Coulomb potential
Smooth models for the Coulomb potential Open
Smooth model potentials with parameters selected to reproduce the spectrum of one-electron atoms are used to approximate the singular Coulomb potential. Even when the potentials do not mimic the Coulomb singularity, much of the spectrum is…
View article: On the Use of Benchmarks for Multiple Properties
On the Use of Benchmarks for Multiple Properties Open
Benchmark calculations provide a large amount of information that can be very useful in assessing the performance of density functional approximations, and for choosing the one to use. In order to condense the information some indicators a…