Modern Tools for Including Electron Correlation in Electronic Structure Studies: Hondo and Chem-Station

Dupuis, Michel; Chin, S.; Márquez, Antonio

doi:10.1007/978-1-4899-1340-1_11

Cited by 99 publications

(103 citation statements)

References 20 publications

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“…The electronic structure calculations used to generate the PESs were carried out with HONDOPLUS v. 5.1 [15,16]. The ISA algorithm was added to HONDO-PLUS from the version in GAMESS [17].…”

Section: Theory and Calculationsmentioning

confidence: 99%

Improved direct diabatization and coupled potential energy surfaces for the photodissociation of ammonia

Valero

Truhlar

2007

Theor Chem Account

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Diabatic potential energy surfaces are a convenient starting point for dynamics calculations of photochemical processes, and they can be calculated by the fourfold way direct diabatization scheme. Here we present an improved definition of the reference orbital for applying the fourfold way direct diabatization scheme to ammonia. The improved reference orbital is a geometry-dependent hybrid orbital that allows one to define consistent dominant configuration lists at all geometries important for photodissociation. Using diabatic energies calculated with the new reference orbital and consistent dominant configuration lists, we have refitted the analytical representations of the ground and the first electronically excited singlet-state potential energy surfaces and the diabatic coupling surface. Improved functional forms were used to reproduce the experimental dissociation energies and excitation energies, which will be important for subsequent simulations of photochemical dynamics. We find that the lowestenergy conical intersection point is at 5.16 eV, with C 2v symmetry. Electronic supplementary materialThe online version of this article

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“…The electronic structure calculations used to generate the PESs were carried out with HONDOPLUS v. 5.1 [15,16]. The ISA algorithm was added to HONDO-PLUS from the version in GAMESS [17].…”

Section: Theory and Calculationsmentioning

confidence: 99%

Improved direct diabatization and coupled potential energy surfaces for the photodissociation of ammonia

Valero

Truhlar

2007

Theor Chem Account

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“…[10] Figure 2 shows the ES-AIMD simulation results at the complete active space self-consistent field (CASSCF) level of theory with the active space comprising six electrons and six active orbitals (6,6), as well as the changes in the structures and natural bond orbital (NBO) charges from the ES-AIMD simulations for HI-A C H T U N G T R E N N U N G (H 2 O) and HIA C H T U N G T R E N N U N G (H 2 O) 2 with the initial kinetic energy of the molecule (KE 0 ) at 0 and 200 K. Ground state AIMD (GS-AIMD) simulations were also performed for H 3 O and H 5 O 2 systems at the CASSCF level with the active space comprising seven electrons and seven active orbitals (7,7). In the simulations, the transition state of the proton between HI and H 2 O was noted, where the kinetic energy of the hydrogen atom was very large (~35 kcal mol…”

Section: Resultsmentioning

confidence: 97%

Photodissociation of Hydrated Hydrogen Iodide Clusters

2008

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Using high-level ab initio calculations and excited state ab initio molecular dynamics simulations, we show that hydrated iodic acids release hydrogen radicals and/or hydrogen molecules as well as iodine radicals upon excitation. Its photoreaction process involving charge transfer to the solvent takes place in four steps: 1) hydration of the acid, 2) charge transfer to water upon excitation of hydrated acid, 3) detachment of the neutral iodine atom, and 4) detachment of the hydrogen radical. The iodine detachment process from excited hydrated hydro-iodic acids is exothermic and the detachment of hydrogen radicals from hydrated hydronium radicals is spontaneous if the initial kinetic energy of the cluster is high enough to get over the activation barrier of the detachment. The complete release of the radicals can be understood in terms of kinetics. This study shows how the hydrogen and halogen radicals are dissociated and released from their hydrated acids. Simple experiments corroborate our predicted mechanism for the release of hydrogen molecules from iodic acid in water by ultraviolet light.

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“…All basis sets, except for hydrogen, were augmented with two d-type polarization functions (1 1). For the electron correlation studies, we implemented the model core potential method into the HONDO (12) program package in order to take advantage of the ability of the HONDO system to remove the spherically symmetric contribution of Cartesian d-type Gaussian functions.…”

Section: Details Of Calculationsmentioning

confidence: 99%

On the performance of molecular model core potential orbitals in spin-orbit and electron correlation studies

Krause¹,

Kłobukowski²

1996

Can. J. Chem.

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~b s t r a c t : The role of improved parametrization and accurate basis sets in model core potentials was studied in calculations of the spin-orbit coupling constants (in PH, ASH, and SbH) and of the electron correlation effects (in P2, Asz, and Sb2). An effective method of identifying and removing the intruder quasi-core orbitals from the virtual orbital space was proposed in connection with the post-Hartree-Fock calculations. The results demonstrated that (a) the flexible valence basis sets allow evaluation of the spin-orbit effects without resorting to any scaling techniques and (b) the intruder quasicore orbitals, even if left imbedded in the virtual space, have negligible effect on the values of the electron correlation energy.Key words: effective core potentials, basis sets, spin-orbit effects, electron correlation. Mots clPs : potentiels efficace des noyaux, ensembles de base, effets spin-orbitale, corrClation Clectronique.[Traduit par la redaction]

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Modern Tools for Including Electron Correlation in Electronic Structure Studies: Hondo and Chem-Station

Cited by 99 publications

References 20 publications

Improved direct diabatization and coupled potential energy surfaces for the photodissociation of ammonia

Improved direct diabatization and coupled potential energy surfaces for the photodissociation of ammonia

Photodissociation of Hydrated Hydrogen Iodide Clusters

On the performance of molecular model core potential orbitals in spin-orbit and electron correlation studies

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