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Computational chemistry and molecular simulations of phosphoric acid
Author(s) -
Li Shuo,
Fried J. R.,
Sauer Jeremy,
Colebrook John,
Dudis Douglas S.
Publication year - 2011
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22702
Subject(s) - chemistry , molecular dynamics , proton , force field (fiction) , density functional theory , molecule , potential energy , phosphoric acid , complete active space , dissociation (chemistry) , computational chemistry , atomic physics , physics , organic chemistry , quantum mechanics , basis set
Quantum mechanics (QM) calculations, molecular dynamics (MD) simulations using the condensed‐phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field, and the atom‐centered density matrix propagation (ADMP) approach have been used to investigate properties of phosphoric acid (PA). QM using B3LYP/6‐31++G(d,p) density functional theory were used to calculate gas‐phase proton affinities and interaction energies of PA and its derivatives. Detailed single coordinate driving, followed by quadratic synchronous transit optimization was used to determine energy barriers for different proton transfer (PT) pathways. Determined energy barrier heights in ascending order are (unit: kJ/mol): H 3 O + →H 3 PO 4 (0); H 4 P 2 O 7 →H 3 PO 4 (2.61); H 3 PO 4 →H 2 PO 4 −(5.31); H 4 PO 4 + →H 3 PO 4 (∼7.33); H 3 PO 4 →H 4 P 2 O 7 /H 3 PO 4 →H 3 PO 4 (15.99); H 4 P 2 O 7 →H 2 O (28.61); H 3 PO 4 →H 2 O (47.14). The COMPASS force field was used to study condensed‐phase properties of PA. Good agreement between experimental data and MD results including density, radial distribution functions, and self‐diffusion coefficient at different temperatures provides validation of the COMPASS force field for PA. Finally, preliminary ADMP studies on a cluster of three PA molecules shows that the ADMP approach can reasonably describe the PT and self‐dissociation processes in PA. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011