LOWDIN: The any particle molecular orbital code

Flores‐Moreno, Roberto; Posada, E.; Moncada, Félix; Romero, Jonathan; Charry, Jorge; Díaz–Tinoco, Manuel; González, Sergio A.; Aguirre, Néstor F.; Reyes, Andrés

doi:10.1002/qua.24500

Cited by 55 publications

(56 citation statements)

References 68 publications

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“…[28,29] Interparticle correlation energies are estimated with several APMO/X methods, namely X = MP2, CISD,C ISDT,C ISDTQ,a nd CISDTQ5. These calculations were performed with am odified version of the LOWDIN package [30] which has implemented ad eterminant-based CI method [40] under the APMO approach. [28] Theexpansion centers for both electrons and the positron are located on the atomic nuclei.…”

Section: Methodsmentioning

confidence: 99%

Binding Matter with Antimatter: The Covalent Positron Bond

2018

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We report sufficient theoretical evidence of the energy stability of the e ⋅H molecule, formed by two H anions and one positron. Analysis of the electronic and positronic densities of the latter compound undoubtedly points out the formation of a positronic covalent bond between the otherwise repelling hydride anions. The lower limit for the bonding energy of the e ⋅H molecule is 74 kJ mol (0.77 eV), accounting for the zero-point vibrational correction. The formation of a non electronic covalent bond is fundamentally distinct from positron attachment to stable molecules, as the latter process is characterized by a positron affinity, analogous to the electron affinity.

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Section: Methodsmentioning

confidence: 99%

Binding Matter with Antimatter: The Covalent Positron Bond

2018

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“…II were implemented in the LOWDIN software package. 44,45,52 PBEs were obtained by solving the quasiparticle Dyson equation (27) for APMO/P2, APMO/P3, APMO/PP3, APMO/OVGF (A, B, and C versions), and APMO/REN-PP3 self-energies, by employing a Newton-Raphson method, with a convergence criterion of 1E-04 eV.…”

Section: A Computational Detailsmentioning

confidence: 99%

“…46 The APMO approach is based on multi-component wavefunctions that employ Gaussian-type functions (GTFs) as basis sets, along the lines of conventional electronic structure methods. This feature allows the calculation of polyatomic systems comprising any type and number of quantum species, such as molecules where electrons and nuclei are treated simultaneously as quantum particles 44,45,[47][48][49][50][51][52][53] and molecules with negative muons. 54, 55 Similar multicomponent methods based on GTFs has been proposed by several research groups, including the Multicomponent Molecular Orbital method (MCMO), 56 the Nuclear Orbital plus Molecular Orbital (NOMO) method, 57 and the Nuclear-Electronic Orbital (NEO) approach.…”

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confidence: 99%

Calculation of positron binding energies using the generalized any particle propagator theory

Romero

Charry

Flores‐Moreno

et al. 2014

The Journal of Chemical Physics

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We recently extended the electron propagator theory to any type of quantum species based in the framework of the Any-Particle Molecular Orbital (APMO) approach [J. Romero, E. Posada, R. Flores-Moreno, and A. Reyes, J. Chem. Phys. 137, 074105 (2012)]. The generalized any particle molecular orbital propagator theory (APMO/PT) was implemented in its quasiparticle second order version in the LOWDIN code and was applied to calculate nuclear quantum effects in electron binding energies and proton binding energies in molecular systems [M. Díaz-Tinoco, J. Romero, J. V. Ortiz, A. Reyes, and R. Flores-Moreno, J. Chem. Phys. 138, 194108 (2013)]. In this work, we present the derivation of third order quasiparticle APMO/PT methods and we apply them to calculate positron binding energies (PBEs) of atoms and molecules. We calculated the PBEs of anions and some diatomic molecules using the second order, third order, and renormalized third order quasiparticle APMO/PT approaches and compared our results with those previously calculated employing configuration interaction (CI), explicitly correlated and quantum Montecarlo methodologies. We found that renormalized APMO/PT methods can achieve accuracies of ~0.35 eV for anionic systems, compared to Full-CI results, and provide a quantitative description of positron binding to anionic and highly polar species. Third order APMO/PT approaches display considerable potential to study positron binding to large molecules because of the fifth power scaling with respect to the number of basis sets. In this regard, we present additional PBE calculations of some small polar organic molecules, amino acids and DNA nucleobases. We complement our numerical assessment with formal and numerical analyses of the treatment of electron-positron correlation within the quasiparticle propagator approach.

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“…In the last fifteen years several ab initio methodologies, with varying degree of success, have been developed aiming to solve Schrödinger's equation for atoms and molecules assuming both electrons and nuclei as quantum waves incorporating their kinetic energy operators simultaneously into the Hamiltonian [1][2][3][4][5][6][7][8]. These methodologies are beyond the usual ab initio procedures; within the Born-Oppenheimer (BO) paradigm electrons are treated as quantum waves and nuclei as clamped point charges, including exclusively the kinetic energy operators of electrons into the Hamiltonian [9].…”

Section: Introductionmentioning

confidence: 99%

Some implications of the Hartree product treatment of the quantum nuclei in the ab initio nuclear–electronic orbital methodology

Gharabaghi

Shahbazian

2016

Physics Letters A

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In this letter the conceptual and computational implications of the Hartree product type nuclear wavefunction introduced recently within the context of the ab initio non-BornOppenheimer Nuclear-electronic orbital (NEO) methodology are considered. It is demonstrated that this wavefunction may imply a pseudo-adiabatic separation of the nuclei and electrons and each nucleus is conceived as a quantum oscillator while a nonCoulombic effective Hamiltonian is deduced for electrons. Using the variational principle this Hamiltonian is employed to derive a modified set of single-component Hartree-Fock equations which are equivalent to the multi-component version derived previously within the context of the NEO and, easy to be implemented computationally.

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LOWDIN: The any particle molecular orbital code

Cited by 55 publications

References 68 publications

Binding Matter with Antimatter: The Covalent Positron Bond

Binding Matter with Antimatter: The Covalent Positron Bond

Calculation of positron binding energies using the generalized any particle propagator theory

Some implications of the Hartree product treatment of the quantum nuclei in the ab initio nuclear–electronic orbital methodology

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