Picture of UK Houses of Parliament

Leading national thinking on politics, government & public policy through Open Access research

Strathprints makes available scholarly Open Access content by researchers in the School of Government & Public Policy, based within the Faculty of Humanities & Social Sciences.

Research here is 1st in Scotland for research intensity and spans a wide range of domains. The Department of Politics demonstrates expertise in understanding parties, elections and public opinion, with additional emphases on political economy, institutions and international relations. This international angle is reflected in the European Policies Research Centre (EPRC) which conducts comparative research on public policy. Meanwhile, the Centre for Energy Policy provides independent expertise on energy, working across multidisciplinary groups to shape policy for a low carbon economy.

Explore the Open Access research of the School of Government & Public Policy. Or explore all of Strathclyde's Open Access research...

Dynamic Charge Equilibration-morse stretch force field : application to energetics of pure silica zeolites

Sefcik, J and Demiralp, E and Cagin, T and Goddard, W A (2002) Dynamic Charge Equilibration-morse stretch force field : application to energetics of pure silica zeolites. Journal of Computational Chemistry, 23 (16). pp. 1507-1514. ISSN 0192-8651

Full text not available in this repository.Request a copy from the Strathclyde author


We present the Dynamic Charge Equilibration (DQEq) method for a self-consistent treatment of charge transfer in force field modeling, where atomic charges are designed to reproduce electrostatic potentials calculated quantum mechanically. Force fields coupled with DQEq allow charges to readjust as geometry changes in classical simulations, using appropriate algorithms for periodic boundary conditions. The full electrostatic energy functional is used to derive the corresponding forces and the second derivatives (hessian) for vibrational calculations. Using DQEq electrostatics, we develop a simple nonbond force field for simulation of silica molecular sieves, where nonelectrostatic interactions are described by two-body Morse stretch terms. Energy minimization calculations with the new force field yield accurate unit cell geometries for siliceous zeolites. Relative enthalpies with respect to quartz and third-law entropies calculated from harmonic vibrational analysis agree very well with available calorimetric data: calculated SiO2 enthalpies relative to a-quartz are within, 2 kJ/mol and entropies at 298 K are within 3 Ymol K of the respective experimental values. Contributions from the zero point energy and vibrational degrees of freedom were found to be only about I kJ/mol for the free energy of mutual transformations between microporous silica polymorphs. The approach presented here can be applied to interfaces and other oxides as well and it is suitable for development of force fields for accurate modeling of geometry and energetics of microporous and mesoporous materials, while providing a realistic description of electrostatic fields near surfaces and inside pores of adsorbents and catalysts.