Implementation of a Morse potential to model hydroxyl behavior in phyllosilicates.
The accurate molecular simulation of many hydrated chemical systems, including clay minerals and other phyllosilicates and their interfaces with aqueous solutions, requires improved classical force field potentials to better describe structure and vibrational behavior. Classical and ab initio molecular dynamics simulations of the bulk structure of pyrophyllite, talc, and Na-montmorillonite clay phases exhibit dissimilar behavior in the hydroxyl stretch region of power spectra derived from atomic trajectories. The classical simulations, using the CLAYFF force field, include either a standard harmonic potential or a new Morse potential parametrized for both dioctahedral and trioctahedral phases for the O-H bond stretch. Comparisons of classical results with experimental values and with ab initio molecular dynamics simulations indicate improvements in the simulation of hydroxyl orientation relative to the clay octahedral sheet and in the O-H bond stretch in the high frequency region of the power spectrum.
Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-0754, USA. jagreat@sandia.gov
Jeffery A
JA
Greathouse
Justin S
JS
Durkin
James P
JP
Larentzos
Randall T
RT
Cygan
D000538:Aluminum Silicates / Q000737:chemistry*; D003198:Computer Simulation; D017665:Hydroxyl Radical / Q000737:chemistry*; D008958:Models, Molecular; D017640:Silicates / Q000737:chemistry*
D000538:Aluminum Silicates; D017640:Silicates; D017665:Hydroxyl Radical