Potential energy surfaces for small alcohol dimers I: Methanol and ethanol

Abstract

Potential energy landscapes for homogeneous dimers of methanol and ethanol were calculated using counterpoise (CP) corrected energies at the MP26-311+G(2df,2pd) level. The landscapes were sampled at approximately 15 dimer separation distances for different relative monomer geometries, or routes, given in terms of a relative monomer yaw, pitch, and roll and the spherical angles between the monomer centers (taken as the C atom attached to the O). The 19 different routes studied for methanol and the 22 routes examined for ethanol include 607 CP corrected energies. Both landscapes can be adequately represented by site-site, pairwise-additive models, suitable for use in molecular simulations. A modified Morse potential is used for the individual pair interactions either with or without point charges to represent the monomer charge distribution. A slightly better representation of the methanol landscape is obtained using point charges, while the potential energy landscape of ethanol is slightly better without point charges. This latter representation may be computationally advantageous for molecular simulations because it avoids difficulties associated with long-range effects of point-charge-type models.

Analytic dynamics of the Morse oscillator derived by semiclassical closures

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][49][50][51][52] Here, we consider two cases for the single Morse oscillator and one example of coupled Morse oscillators.…”

Potential energy surfaces for small alcohol dimers. II. Propanol, isopropanol, t-butanol, and sec-butanol

“…In a companion paper, 1 we reported counterpoisecorrected dimer potential energy landscapes for rigid monomers of methanol and ethanol. These dimer energy surfaces were obtained from ab initio supermolecule calculations using MP2 / 6-311+ G͑2df ,2pd͒.…”

“…We refer readers to the discussion and references cited in Ref. 1 for background on appropriate methods for obtaining dimer energy landscapes and their validation in simulation work.…”

“…With this in mind, in Ref. 1 we regressed the ab initio methanol and ethanol energy landscapes to obtain parameters in Eq. ͑2͒ in two different ways, both of which adequately represented the complexity of the dimer energy surfaces.…”

10.3726/978-3-653-04937-4/14

“…• tion interaction for very small molecules [412,413], Møller-Plesset perturbation theory [414] or Monte Carlo methods [415,416]. Attempts to use ground state density functional theory (DFT) are specially challenging [410,411]; In the realm of time-dependent density-functional theory (TDDFT), the recent work of Dobson [417] summarizes the current research, largely based on the adiabatic connection / fluctuation dissipation theorem.…”