Fast electron correlation methods for molecular clusters in the ground and excited states

Hirata, So; Valiev, Marat; Dupuis, Michel; Xantheas, Sotiris S.; Sugiki, Shinichiro; Sekino, Hideo

doi:10.1080/00268970500083788

Cited by 144 publications

(162 citation statements)

References 74 publications

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“…These monomers and dimers are placed in the electrostatic field of the rest of the crystal represented by atomic charges computed by the method developed by Kamiya et al 47 at the Hartree-Fock (HF) level with the same basis set. These atomic charges are furthermore brought to self consistency with one another 36 . We have taken into account the atomic charges within the 11 Â 11 Â 11 supercell, consisting of 5,324 molecules.…”

Section: Methodsmentioning

confidence: 99%

“…Our MP2 calculation of the Gibbs free energy of a molecular crystal is based on an embedded-fragment scheme [36][37][38] , which, in turn, uses the Bethe-Goldstone expansion of the total energy 45,46 .…”

Section: Methodsmentioning

confidence: 99%

“…This article reports an advance in computational machinery 36,37 that enables routine ab initio calculations of the free energies of general molecular crystals at finite pressures 38 and temperatures and thus of phase diagrams from first principles. We demonstrate the utility of this method through its application to the structures, equations of state and Raman spectra of both phases I and III of CO 2 as well as the solid-solid phase transition between them.…”

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confidence: 99%

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A solid–solid phase transition in carbon dioxide at high pressures and intermediate temperatures

Sode

Voth

et al. 2013

Nat Commun

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Despite its terrestrial abundance and astrochemical significance, many aspects of the phase diagram of solid carbon dioxide remain uncertain or unknown. The observed transition pressures from cubic to orthorhombic phase range widely from 2.5 GPa at 80 K to above 18 GPa at room temperature. The vibrational Raman bands that appear at higher pressure and serve as a decisive proof of the existence of the orthorhombic phase have never been assigned. Here we introduce a general ab initio computational method that can predict the Gibbs free energies and thus phase diagrams of molecular crystals. Using this with secondorder Møller-Plesset perturbation theory, we obtain the transition pressure of 13 GPa at 0 K with small temperature dependence, which is in line with many experiments. We also computationally reproduce the vibrational Raman bands and explain the pressure dependence of the structure parameters and Raman band positions of both phases quantitatively.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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A solid–solid phase transition in carbon dioxide at high pressures and intermediate temperatures

Sode

Voth

et al. 2013

Nat Commun

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“…The excitation energy difference between the gas and solution phases, the solvatochromic shift, is calculated to be 0.34 eV, which is comparable to the experimental value of 0.21 eV for acetone 56 as well as to previous theoretical results. 20,[34][35][36][37][38][39][40][41][42] …”

Section: Absorption Spectra Of Formaldehyde In Gas Phase and In Somentioning

confidence: 99%

“…Although there are no experimental fluorescence spectra available for aqueous formaldehyde, this solute-solvent system has been the subject of several theoretical studies. 20,21,[33][34][35][36][37][38][39][40][41][42][43][44][45] The ultimate goal is to apply the TDDFT/EFP1 method to large-scale QM/MM simulations in excited states. Therefore, the present study on this simple system is an initial step toward applications to more complex systems.…”

Section: Introductionmentioning

confidence: 99%

Implementation of the analytic energy gradient for the combined time-dependent density functional theory/effective fragment potential method: Application to excited-state molecular dynamics simulations

Silva

Zahariev

2011

The Journal of Chemical Physics

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Excited-state quantum mechanics/molecular mechanics molecular dynamics simulations are performed, to examine the solvent effects on the fluorescence spectra of aqueous formaldehyde. For that purpose, the analytical energy gradient has been derived and implemented for the linear-response time-dependent density functional theory (TDDFT) combined with the effective fragment potential (EFP) method. The EFP method is an efficient ab initio based polarizable model that describes the explicit solvent effects on electronic excitations, in the present work within a hybrid TDDFT/EFP scheme. The new method is applied to the excited-state MD of aqueous formaldehyde in the n-π* state. The calculated π*→n transition energy and solvatochromic shift are in good agreement with other theoretical results. KeywordsExcited states, Excitation energies, Solvents, Polarization, Absorption spectra Excited-state quantum mechanics/molecular mechanics molecular dynamics simulations are performed, to examine the solvent effects on the fluorescence spectra of aqueous formaldehyde. For that purpose, the analytical energy gradient has been derived and implemented for the linear-response time-dependent density functional theory (TDDFT) combined with the effective fragment potential (EFP) method. The EFP method is an efficient ab initio based polarizable model that describes the explicit solvent effects on electronic excitations, in the present work within a hybrid TDDFT/EFP scheme. The new method is applied to the excited-state MD of aqueous formaldehyde in the n-π * state. The calculated π *→n transition energy and solvatochromic shift are in good agreement with other theoretical results.

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The Energy‐Based Fragmentation Approach for Ab Initio Calculations of Large Systems

Li¹,

Hua²,

Fang³

et al. 2011

Computational Methods for Large Systems

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Fast electron correlation methods for molecular clusters in the ground and excited states

Cited by 144 publications

References 74 publications

A solid–solid phase transition in carbon dioxide at high pressures and intermediate temperatures

A solid–solid phase transition in carbon dioxide at high pressures and intermediate temperatures

Implementation of the analytic energy gradient for the combined time-dependent density functional theory/effective fragment potential method: Application to excited-state molecular dynamics simulations

The Energy‐Based Fragmentation Approach for Ab Initio Calculations of Large Systems

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