Efficient implementation of the interacting quantum atoms energy partition of the second‐order Møller–Plesset energy

Casals‐Sainz, José Luis; Guevara‐Vela, José Manuel; Francisco, E.; Rocha‐Rinza, Tomás; Pendás, Ángel Martín

doi:10.1002/jcc.26169

Cited by 17 publications

(10 citation statements)

References 56 publications

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“…The problem with this initial IQA/MP2 approach is that its computational cost is practically the same as the one corresponding to an IQA/CCSD partition. However, a new algorithm has been recently developed that takes only into account occupied to virtual excitations [ 42 ]. The new IQA/MP2 method allows for dramatic reductions in computer time, although it has the disadvantage of providing first order properties similar to those of the HF approach.…”

Section: The Iqa Methodologymentioning

confidence: 99%

Interacting Quantum Atoms—A Review

et al. 2020

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The aim of this review is threefold. On the one hand, we intend it to serve as a gentle introduction to the Interacting Quantum Atoms (IQA) methodology for those unfamiliar with it. Second, we expect it to act as an up-to-date reference of recent developments related to IQA. Finally, we want it to highlight a non-exhaustive, yet representative set of showcase examples about how to use IQA to shed light in different chemical problems. To accomplish this, we start by providing a brief context to justify the development of IQA as a real space alternative to other existent energy partition schemes of the non-relativistic energy of molecules. We then introduce a self-contained algebraic derivation of the methodological IQA ecosystem as well as an overview of how these formulations vary with the level of theory employed to obtain the molecular wavefunction upon which the IQA procedure relies. Finally, we review the several applications of IQA as examined by different research groups worldwide to investigate a wide variety of chemical problems.

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Section: The Iqa Methodologymentioning

confidence: 99%

Interacting Quantum Atoms—A Review

et al. 2020

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“…Of course it is possible to go beyond this resolution (i.e., towards a third level) and introduce

V_{inter}^{AB}

as explicit interatomic potential energies. IQA also allows the contributions to be broken down even further [ 30,31 ] (not shown in Equation )), namely into kinetic, exchange‐correlation (which can be split in exchange and correlation [ 32–35 ] ) and electrostatic components. This finer partitioning provides more chemical insight but at a computational cost.…”

Section: Methodsmentioning

confidence: 99%

On the many‐body nature of intramolecular forces in FFLUX and its implications

2020

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FFLUX is a biomolecular force field under construction, based on Quantum Chemical Topology (QCT) and machine learning (kriging), with a minimalistic and physically motivated design. A detailed analysis of the forces within the kriging models as treated in FFLUX is presented, taking as a test example a liquid water model. The energies of topological atoms are modeled as 3N atoms-6 dimensional potential energy surfaces, using atomic local frames to represent the internal degrees of freedom. As a result, the forces within the kriging models in FFLUX are inherently N-body in nature where N refers to N atoms. This provides a fuller picture that is closer to a true quantum mechanical representation of interactions between atoms. The presented computational example quantitatively showcases the non-negligible (as much as 9%) three-body nature of bonded forces and angular forces in a water molecule. We discuss the practical impact on the pressure calculation with N-body forces and periodic boundary conditions (PBC) in molecular dynamics, as opposed to classical force fields with two-body forces. The equivalence between the PBC-related correction terms in the general virial equation is shown mathematically.

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“…Although values were already calculated at full CI level for H 2 and He 2 in the original IQA paper [44] of 2005, MP2 (as well as MP3 and MP4SDQ) energies only became available [80] in 2016 for the first time. Even more recently, others have proposed [159] an efficient implementation of the MP2 energy, with a nearly linear scaling with respect to the number of basis functions. This work already enabled modest computing times to obtain V AB c values for various classical configurations of ethane dimers, and opens an avenue towards more elaborate studies of non-covalent interactions.…”

Section: Electron Correlation Energymentioning

confidence: 99%

Non-covalent interactions from a Quantum Chemical Topology perspective

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2022

J Mol Model

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About half a century after its little-known beginnings, the quantum topological approach called QTAIM has grown into a widespread, but still not mainstream, methodology of interpretational quantum chemistry. Although often confused in textbooks with yet another population analysis, be it perhaps an elegant but somewhat esoteric one, QTAIM has been enriched with about a dozen other research areas sharing its main mathematical language, such as Interacting Quantum Atoms (IQA) or Electron Localisation Function (ELF), to form an overarching approach called Quantum Chemical Topology (QCT). Instead of reviewing the latter’s role in understanding non-covalent interactions, we propose a number of ideas emerging from the full consequences of the space-filling nature of topological atoms, and discuss how they (will) impact on interatomic interactions, including non-covalent ones. The architecture of a force field called FFLUX, which is based on these ideas, is outlined. A new method called Relative Energy Gradient (REG) is put forward, which is able, by computation, to detect which fragments of a given molecular assembly govern the energetic behaviour of this whole assembly. This method can offer insight into the typical balance of competing atomic energies both in covalent and non-covalent case studies. A brief discussion on so-called bond critical points is given, highlighting concerns about their meaning, mainly in the arena of non-covalent interactions.

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Efficient implementation of the interacting quantum atoms energy partition of the second‐order Møller–Plesset energy

Cited by 17 publications

References 56 publications

Interacting Quantum Atoms—A Review

Interacting Quantum Atoms—A Review

On the many‐body nature of intramolecular forces in FFLUX and its implications

Non-covalent interactions from a Quantum Chemical Topology perspective

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