Andre Severo Pereira Gomes

University of Lille · Department of Physics

We investigate the core-level ionization energies of the bare uranyl ion (UO$_2^{2+}$) and its interaction with X-rays when it is hosted in the Cs$_2$UO$_2$Cl$_4$ crystalline environment using a recent implementation of the core-valence-separated relativistic equation-of-motion coupled-cluster method (CVS-EOM-CC). Our study evaluates different rela...

The bond distance is the simplest and most obvious indicator of the nature of a given chemical bond. However, for rare chemistry, it may happen that it is not yet...

The bond distance is the simplest and most obvious indicator of the nature of a given chemical bond. However, for rare chemistry, it may happen that it is not yet firmly established. In this communication, we will show that the formally-triple protactinium(V) mono-oxo bond is predicted longer than what was previously reported in the solid state and...

Quantum-chemical subsystem and embedding methods require complex workflows that may involve multiple quantum-chemical program packages. Moreover, such workflows require the exchange of voluminous data that go beyond simple quantities, such as molecular structures and energies. Here, we describe our approach for addressing this interoperability chal...

We present the development and implementation of the relativistic coupled cluster linear response theory (CC-LR) which allows the determination of molecular properties arising from time-dependent or time-independent electric, magnetic, or mixed electric-magnetic perturbations (within a common gauge origin), and take into account the finite lifetime...

X-ray spectroscopies, by their high selectivity and sensitivity to the chemical environment around the atoms probed, provide significant insights into the electronic structures of molecules and materials. Interpreting experimental results requires reliable theoretical models, accounting for environmental, relativistic, electron correlation, and orb...

The equation of motion coupled cluster singles and doubles model (EOM-CCSD) is an accurate, black-box correlated electronic structure approach to investigate electronically excited states and electron attachment or detachment processes. It has also served as a basis for developing less computationally expensive approximate models such as partitione...

Bent uranyl complexes can be formed with chloride ligands and 1,10-phenanthroline (phen) ligands bound to the equatorial and axial planes of the uranyl(VI) moiety, as revealed by the crystal structures, IR and Raman spectroscopy, and quantum-chemical calculations. With the goal of probing the influence of chloride and phenanthroline coordination en...

Bent uranyl complexes can be formed with chloride ligands and 1,10-phenanthroline (phen) ligands bound to the equatorial and axial planes of the uranyl(VI) moiety, as revealed by the crystal structures, IR and Raman spectroscopy and quantum chemical calculations. With the goal of probing the influence of chloride and phenanthroline coordination enf...

Bent uranyl complexes can be formed with chloride ligands and 1,10-phenanthroline (phen) ligands bound to the equatorial and axial planes of the uranyl(VI) moiety, as revealed by the crystal structures, IR and Raman spectroscopy and quantum chemical calculations. With the goal of probing the influence of chloride and phenanthroline coordination enf...

X-ray spectroscopies, by their high selectivity and sensitivity to the chemical environment around the atoms probed, provide significant insight into the electronic structure of molecules and materials. Interpreting experimental results requires reliable theoretical models, accounting for environment, relativistic, electron correlation, and orbital...

We have computed the cross sections of the mutual neutralization reaction between I+ and I− for a collision energy varying from 0.001 eV to 50 eV. These cross sections were obtained using the adiabatic potential energy curves of the I2 system computed with a direct relativistic multireference configuration interaction method and a semiclassical app...

We have computed the cross sections of the mutual neutralization reaction between I$^{+}$ and I$^{-}$ for a collision energy varying from 0.001 eV to 50 eV. These cross sections were obtained using the adiabatic potential energy curves of the I$_{2}$ system computed with a direct relativistic Multi-Reference Configuration Interaction method and a s...

Reaction of [(XA2)U(CH2SiMe3)2] (1; XA2 = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) with 1 equivalent of [Ph3C][B(C6F5)4] in arene solvents afforded the arene-coordinated uranium alkyl cations, [(XA2)U(CH2SiMe3)(η n -arene)][B(C6F5)4] {arene = benzene (2), toluene (3), bromobenzene (4) and fluorobenzene (5)}. Compounds...

Frozen density embedding (FDE) represents an embedding scheme in which environmental effects are included from first-principles calculations by considering the surrounding system explicitly by means of its electron density. In the present paper, we extend the full four-component relativistic Dirac-Kohn-Sham (DKS) method, as implemented in the BERTH...

The TlCl molecule has previously been investigated theoretically and proposed as promising candidates for laser cooling searches [X. Yuan et. al. J. Chem. Phys., 149, 094306, 2018]. From these results, the cooling process, which would proceed by transitions between a ³ Π ⁺ 0 and X ¹ Σ ⁺ 0 states, had as potential bottleneck the long lifetime (6.04...

We have studied the mutual neutralization reaction of atomic iodine ions (i.e., I++I−→I+I) in a cryogenic double electrostatic ion-beam storage-ring apparatus. Our results show that the reaction forms iodine atoms either in the ground-state configuration (I(5p52P∘), ∼40%) or with one atom in an electronically excited state (I(6s2[2]), ∼60%), with n...

In this work we investigate the effects of the environment on the X-ray photoelectron spectra of hydrogen chloride and the chloride ions adsorbed on ice surfaces, as well as of chloride ions in water droplets. In our approach, we combine a density functional theory (DFT) description of the ice surface with that of the halogen species with the recen...

In this work, we investigate the effects of the environment on the X-ray photoelectron spectra of hydrogen chloride and chloride ions adsorbed on ice surfaces, as well as of chloride ions in water droplets. In our approach, we combine a density functional theory (DFT) description of the ice surface with that of halogen species using the recently de...

The high computational scaling with basis set size and the number of correlated electrons is a bottleneck limiting applications of coupled cluster (CC) algorithms, in particular for calculations based on 2- or 4-component relativistic Hamiltonians, which often employ uncontracted basis sets. This problem may be alleviated by replacing canonical Har...

The Frozen Density Embedding scheme represents an embedding method in which environmental effects onto a given subsystem are included by representing the other subsystems making up the surroundings quantum mechanically, by means of their electron densities. In the present paper, we extend the full 4-component relativistic Dirac-Kohn-Sham method, as...

The TlCl molecule has previously been investigated theoretically and proposed as promising candidates for laser cooling searches [X. Yuan et. al. J. Chem. Phys., 149, 094306, 2018]. From these results, the cooling process, which would proceed by transitions between a\sup{3}{\Pi}\sup{+}\sub{0} and X\sup{1}{\Sigma}\sup{+}\sub{0} states, had as potent...

In this work we implement the real-time time-dependent block-orthogonalized Manby-Miller embedding (rt-BOMME) approach alongside our previously developed real-time frozen density embedding time-dependent density functional theory (rt-TDDFT-in-DFT FDE) code, and investigate these methods’ performance in reproducing X-ray absorption spectra (XAS) obt...

The high computational scaling with the number of correlated electrons and the size of the basis set is a bottleneck which limits applications of coupled cluster (CC) algorithms. This is particularly so for calculations based on 4-component relativistic Hamiltonians, which generally employ uncontracted basis sets and lead to large virtual molecular...

We report an investigation of the suitability of quantum embedding for modeling the effects of the environment on the X-ray photoelectron spectra of hydrogen chloride and the chloride ions adsorbed on ice surfaces, as well as of chloride ions in water droplets. In our approach, we combine a density functional theory (DFT) description of the ice sur...

In this work we implement the real-time time-dependent block-orthogonalized Manby-Miller embedding (rt-BOMME) approach alongside our previously developed real-time frozen density embedding time-dependent density functional theory (rt-TDDFT-in-DFT FDE) code, and investigate these methods' performance in reproducing X-ray absorption spectra (XAS) obt...

We report an investigation of the low-lying excited states of the YbF molecule-a candidate molecule for experimental measurements of the electron electric dipole moment-with 2-component based multi-reference configuration interaction (MRCI), equation of motion coupled cluster (EOM-CCSD) and the extrapolated intermediate Hamiltonian Fock-space coupl...

In this paper, we report reimplementation of the core algorithms of relativistic coupled cluster theory aimed at modern heterogeneous high-performance computational infrastructures. The code is designed for parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end. The resulting ExaCorr mod...

We report an investigation of the low-lying excited states of the YbF molecule--a candidate molecule for experimental measurements of the electron electric dipole moment--with 2-component based multi-reference configuration interaction (MRCI), equation of motion coupled cluster (EOM-CCSD) and the extrapolated intermediate Hamiltonian Fock-space cou...

In this paper, we report a reimplementation of the core algorithms of relativistic coupled cluster theory aimed at modern heterogeneous high-performance computational infrastructures. The code is designed for efficient parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end. The resulting...

We report an implementation of the core-valence separation approach to the 4-component relativistic Hamiltonian based equation-of-motion coupled-cluster with singles and doubles theory (CVS-EOM-CCSD), for the calculation of relativistic core-ionization potentials and core-excitation energies. With this implementation, which is capable of exploiting...

The cover image is based on the Full Paper Investigating solvent effects on the magnetic properties of molybdate ions () with relativistic embedding by Loïc Halbert et al., https://doi.org/10.1002/qua.26207.

Frozen Density Embedding (FDE) represents a versatile embedding scheme to describe the environmental effect on the electron dynamics in molecular systems. The extension of the general theory of FDE to the real-time time-dependent Kohn-Sham method has previously been presented and implemented in plane-waves and periodic boundary conditions (Pavanell...

Frozen Density Embedding (FDE) represents a versatile embedding scheme to describe the environmental effect on the electron dynamics in molecular systems. The extension of the general theory of FDE to the real-time time-dependent Kohn-Sham method has previously been presented and implemented in plane-waves and periodic boundary conditions (Pavanell...

DIRAC is a freely distributed general-purpose program system for one-, two-, and four-component relativistic molecular calculations at the level of Hartree–Fock, Kohn–Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, electron propagator, and various flavors of coupled clus...

We investigate the ability of mechanical and electronic density functional theory‐based embedding approaches to describe the solvent effects on nuclear magnetic resonance (NMR) shielding constants of the 95Mo nucleus in the molybdate ion in aqueous solution. From the description obtained from calculations with two‐ and four‐component relativistic H...

DIRAC is a freely distributed general-purpose program system for 1-, 2- and 4-component relativistic molecular calculations at the level of Hartree--Fock, Kohn--Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, coupled cluster and electron propagator theory. At the self-co...

We investigate the ability of mechanical and electronic density functional theory (DFT)-based embedding approaches to describe the solvent effects on nuclear magnetic resonance (NMR) shielding constants of the $^{95}$Mo nucleus in the molybdate ion in aqueous solution. From the description obtained from calculations with two- and four-component rel...

Topological Data Analysis (TDA) is a powerful mathematical theory, largely unexplored in theoretical chemistry. In this work we demonstrate how TDA provides new insights into topological features of electron densities and reduced density gradients, by investigating the effects of relativity on the bonding of the Au4‐S‐C6H4‐S′‐Au′4 molecule. Whereas...

DIRAC19 DIRAC, a relativistic ab initio electronic structure program, Release DIRAC19 (2019), written by A. S. P. Gomes, T. Saue, L. Visscher, H. J. Aa. Jensen, and R. Bast, with contributions from I. A. Aucar, V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, E. Faßhauer, T. Fleig, O. Fossgaard, L. Halbert, E. D. Hedegård,...

The ability to predict the nature and amounts of plutonium emissions in industrial accidents, such as in solvent fires at PUREX nuclear reprocessing facilities, is a key concern of nuclear safety agencies. In accident conditions and in the presence of oxygen and water vapor, plutonium is expected to form the three major volatile species PuO2, PuO3,...

DIRAC18 DIRAC, a relativistic ab initio electronic structure program, Release DIRAC18 (2018), written by T. Saue, L. Visscher, H. J. Aa. Jensen, and R. Bast, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, E. Faßhauer, T. Fleig, O. Fossgaard, A. S. P. Gomes, E. D. Hedegård, T. Helgaker, J. Henrikss...

Topological Data Analysis (TDA) is a powerful mathematical theory, largely unexplored in theoretical chemistry. In this work we demonstrate how TDA provides new insights into topological features of electron densities and reduced density gradients, by investigating the effects of relativity on the bonding of the Au4-S-C6H4-S'-Au'4 molecule. Whereas...

Having the ability to predict the nature and amounts of plutonium emissions in industrial accidents, such as in solvent fires at PUREX nuclear reprocessing facilities, is a key concern of nuclear safety agencies. In accident conditions and in the presence of oxygen and water vapor, plutonium is expected to form three major volatile species $\rm{PuO...

We report in this paper an implementation of a 4-component relativistic Hamiltonian based Equation-of-Motion Coupled-Cluster with singles and doubles (EOM-CCSD) theory for the calculation of ionization potential, electron affinity, and excitation energy. In this work, we utilize the previously developed double group symmetry-based generalized tenso...

A subsystem approach for obtaining electron binding energies in the valence region is presented and applied to the case of halide ions (X−,X=F−At) in water. This approach is based on electronic structure calculations combining the relativistic equation-of-motion coupled cluster method for electron detachment and density functional theory via the fr...

We present a subsystem approach for obtaining electron binding energies in the valence region and apply it to the case of halide ions (X$^-$, X = F-At) in water. This approach is based on electronic structure calculations combining the relativistic equation of motion coupled-cluster method for electron detachment (EOM-IP-CCSD) and density functiona...

We report in this paper an implementation of 4-component relativistic Hamiltonian based Equation-of-Motion Coupled-Cluster (EOMCC) theory for the calculation of ionization potential (IP), electron affinity (EA) and excitation energy (EE). In this work we utilize previously developed double group symmetry-based generalized tensor contraction scheme,...

We report an implementation of the nuclear magnetic resonance (NMR) shielding ($\sigma$), isotope-independent indirect spin-spin coupling ($K$) and the magnetizability ($\xi$) tensors in the frozen density embedding (FDE) scheme using the four-component (4c) relativistic Dirac--Coulomb (DC) Hamiltonian and the non-collinear spin density functional...

We report an implementation of the nuclear magnetic resonance (NMR) shielding ($\sigma$), isotope-independent indirect spin-spin coupling ($K$) and the magnetizability ($\xi$) tensors in the frozen density embedding (FDE) scheme using the four-component (4c) relativistic Dirac--Coulomb (DC) Hamiltonian and the non-collinear spin density functional...

Actinide-containing complexes present formidable challenges for electronic structure methods due to the large number of degenerate or quasi-degenerate electronic states arising from partially occupied 5f and 6d shells. Conventional multi-reference methods can treat active spaces that are often at the upper limit of what is required for a proper tre...

Actinide-containing complexes present formidable challenges for electronic structure methods due to the large number of degenerate or quasi-degenerate electronic states arising from partially occupied 5f and 6d shells. Conventional multi-reference methods can treat active spaces that are often at the upper limit of what is required for a proper tre...

The properties of halides from the lightest, uoride (F−), to the heaviest, astatide (At−), have been studied in water using a polarizable force- eld approach based on molecular dynamics (MD) simulations at the 10 ns scale. The selected force- eld explicitly treats the cooperativity within the halide-water hydrogen bond networks. The force- eld para...

DIRAC, a relativistic ab initio electronic structure program, Release DIRAC16 (2016), written by H. J. Aa. Jensen, R. Bast, T. Saue, and L. Visscher, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekstroem, E. Eliav, T. Enevoldsen, E. Fasshauer, T. Fleig, O. Fossgaard, A. S. P. Gomes, T. Helgaker, J. Henriksson, M. Ilias, Ch. R. J...

The low-lying electronic states of ThF+, a possible candidate in the search for - and -violation, have been studied using high-level correlated relativistic ab initio multi-reference coupled-cluster and configuration interaction approaches. For the state component with Ω = 1 (electron electric dipole moment 'science state') we obtain an effective e...

The theoretical modeling of lanthanide and actinide complexes in condensed media is challenging for theoretical chemistry, due in part to the intrinsic general challenge of devising a reliable model of the species in such environments and the necessity of 'chemical' accuracy. This chapter discusses the requirements, challenges, and pitfalls associa...

The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin-orbit wave functions resulting from spin-orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin-orbit coupling framework...

DIRAC, a relativistic ab initio electronic structure program, Release DIRAC15 (2015), written by R. Bast, T. Saue, L. Visscher, and H. J. Aa. Jensen, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekstroem, E. Eliav, T. Enevoldsen, E. Fasshauer, T. Fleig, O. Fossgaard, A. S. P. Gomes, T. Helgaker, J. Henriksson, M. Ilias, Ch. R. J...

We present a study of the electronic structure of the [UO2]+,[UO2]2 +,[UO2]3 +, NUO, [NUO]+, [NUO]2 +, [NUN]−, NUN, and [NUN]+ molecules with the intermediate Hamiltonian Fock-space coupled cluster method. The accuracy of mean-field approaches based on the eXact-2-Component Hamiltonian to incorporate spin–orbit coupling and Gaunt interactions are c...

The electronic structure of the XO and XO(+) (X = I, At) species, as well that of a AtO(+)-H2O complex have been investigated using relativistic wave-function theory and density functional theory (DFT)-based approximations (DFAs). The n-electron valence state perturbation method with the perturbative inclusion of spin-orbit coupling including spin-...

DIRAC, a relativistic ab initio electronic structure program, Release DIRAC14 (2014), written by T. Saue, L. Visscher, H. J. Aa. Jensen, and R. Bast, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, E. Faßhauer, T. Fleig, O. Fossgaard, A. S. P. Gomes, T. Helgaker, J. Henriksson, M. Iliaš, Ch. R. Jac...

Building on the framework recently reported for determining general response properties for frozen-density embedding [S. Höfener, A. S. P. Gomes, and L. Visscher, J. Chem. Phys. 136, 044104 (2012)], in this work we report a first implementation of an embedded coupled-cluster in density-functional theory (CC-in-DFT) scheme for electronic excitations...

In this work we explore the use of frozen density embedding [Gomes et al., Phys. Chem. Chem. Phys., 2008, 10, 5353] as a way to construct models of increasing sophistication for describing the low-lying electronic absorption spectra of UO2(2+) in the Cs2UO2Cl4 crystal. We find that a relatively simple embedding model, in which all but the UO2(2+) u...

DIRAC, a relativistic ab initio electronic structure program, Release DIRAC13 (2013), written by L. Visscher, H. J. Aa. Jensen, R. Bast, and T. Saue, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, E. Faßhauer, T. Fleig, O. Fossgaard, A. S. P. Gomes, T. Helgaker, J. K. Lærdahl, Y. S. Lee, J. Henrik...

The electronic spectrum of the CUO molecule was investigated with the IHFSCC-SD (intermediate Hamiltonian Fock-space coupled cluster with singles and doubles) method and with TD-DFT (time-dependent density functional theory) employing the PBE and PBE0 exchange-correlation functionals. The importance of both spin-orbit coupling and correlation effec...

Quantum chemistry has become an invaluable tool for studying the electronic excitation phenomena underlying many important chemical, biological, and technological processes. Here, we review quantum-chemical approaches for modeling such phenomena. In particular, embedding methods can be particularly useful for treating localized excitations in compl...

In this article, we present a consistent derivation of a density functional theory (DFT) based embedding method which encompasses wave-function theory-in-DFT (WFT-in-DFT) and the DFT-based subsystem formulation of response theory (DFT-in-DFT) by Neugebauer [J. Neugebauer, J. Chem. Phys. 131, 084104 (2009)] as special cases. This formulation, which...

DIRAC, a relativistic ab initio electronic structure program, Release DIRAC12 (2012), written by H. J. Aa. Jensen, R. Bast, T. Saue, and L. Visscher, with contributions from V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, T. Fleig, O. Fossgaard, A. S. P. Gomes, T. Helgaker, J. K. Lærdahl, Y. S. Lee, J. Henriksson, M. Ilia...