Determination of an ethane intermolecular potential model for use in molecular simulations from ab initio calculations

Abstract

Counterpoise-corrected, supermolecule, ab initio energies obtained at the MP2/6-311ϩG(2d f ,2pd) level were computed for 22 different relative orientations of two ethane molecules as a function of the separation distance between the molecular centers. These energies were used to regress the parameters in several simple, analytical, interatomic or site-site models that can be used for implementation in molecular simulations. Sensitivity analysis indicates that the intermolecular potential surface is insensitive to CC interactions and that the parameters in the CC model are coupled and unobtainable from the dimer energies. Representation of the potential surface can be made in terms of C-H and H-H interatomic potentials if the CC interactions are treated as shielded. Simple Lennard-Jones and exp-6 models do not adequately represent the potential surface using these shielded models, nor do they produce the anticipated physics for the interatomic potentials. The exp-6 model with a damping function and the modified-Morse interatomic potentials both reproduce the intermolecular potential surface well with physically realistic intersite potentials suitable for use in molecular dynamics simulations.

Estimated MP2 and CCSD(T) interaction energies of n-alkane dimers at the basis set limit: Comparison of the methods of Helgaker et al. and Feller

“…27,28 The intermolecular interaction energy of the methane dimer has been calculated repeatedly as the smallest model of the interaction between alkane molecules. [29][30][31][32][33][34][35][36][37][38][39][40][41] Recently a few calculations of the ethane [36][37][38][39][40][41][42][43] and propane dimers 41,44,45 were reported. The calculations of these small alkane dimers show that dispersion ͑van der Waals attraction͒ is the major source of the attraction.…”

Validation of intermolecular pair potential model of SiH4: Molecular-dynamics simulation for saturated liquid density and thermal transport properties

“…Silicon epitaxial wafers and various other silicon thin films have been formed from SiH 4 or its mixtures. The models of C 2 H 6 were also proposed by Rowley et al 6 and Padua and Trusler, 7 and C 2 H 5 OH by Mooij et al 8 With this background, we have constructed an intermolecular pair potential model of SiH 4 from ab initio molecular-orbital ͑MO͒ calculations in the framework of the multiscale modeling of the LPCVD process in our previous report. Over the past few decades, a considerable number of studies have been devoted to the construction of potential models for silicon and its compounds, which is sensitive to the accuracy of the atomic simulation.…”

A theoretical investigation on optimal structures of ethane clusters (C2H6)n with n ≤ 25 and their building‐up principle

“…The global-minimum configuration of the dimer is consistent with that reported in ref. 7. The global minima of the n 5 2, 3, 4, 5 clusters were found 39, 33, 6, and 9 times, respectively.…”

“…In the development of the potential functions, molecular structure of ethane is assumed to be rigid and structural parameter values 7 are as follows: r(CÀ ÀC) 5 1.5227 Å ; r(CÀ ÀH) 5 1.0883 Å ; ffCCH 5 111.2528; /(HCCH) 5 6608, 1808.…”