http://hdl.handle.net/2160/14 2013-05-12T17:55:07Z 2013-05-12T17:55:07Z Flikkema, Edwin Bromley, Stefan http://hdl.handle.net/2160/13845 2013-05-10T15:56:35Z 2011-06-30T00:00:00Z

Global Optimization of (hydroxylated) Silica Clusters Flikkema, Edwin; Bromley, Stefan

2011-06-30T00:00:00Z Flikkema, Edwin Greaves, Neville Zhou, Zhongfu http://hdl.handle.net/2160/13844 2013-05-10T15:56:33Z 2011-06-30T00:00:00Z

Molecular Dynamics Study of Ion Diffusion in Glassy Materials Flikkema, Edwin; Greaves, Neville; Zhou, Zhongfu

2011-06-30T00:00:00Z Flikkema, E. http://hdl.handle.net/2160/13777 2013-05-10T15:55:00Z 2010-07-17T00:00:00Z

Computational studies of silicate materials: clusters and bulk Flikkema, E.

2010-07-17T00:00:00Z Flikkema, E. Wales, D. J. http://hdl.handle.net/2160/13776 2013-05-10T15:54:59Z 2009-09-07T00:00:00Z

Energy landscapes and basin sampling of bulk mixed oxide systems Flikkema, E.; Wales, D. J. This poster focuses on an energy landscape study of bulk oxide systems, a specific example being a mixture of calcium oxide and magnesium oxide (CaO/MgO). These oxide systems are modeled at the level of empirical potentials (taken from the literature) consisting of a Buckingham potential combined with electrostatics and a shell model for polarizability. This system was studied before by Mohn and Stolen using a genetic algorithm [1]. In this poster we present results obtained by applying the Basin Sampling (BS) methodology [2] to the CaO/MgO system. The BS method attempts to calculate the potential energy density of minima using a Wang-Landau-type sampling algorithm [3]. An approximate method is used for compensating for differences in volume of the basins of attraction of the minima, with the final aim of calculating the partition function using a thermodynamic superposition principle. Applying the BS method to the bulk CaO/MgO mixed oxide system proved challenging: the iterative Wang-Landau method proved to be time-consuming and the resulting density of minima is of a limited accuracy. Possible routes for improving the sampling will be discussed. As an alternative way for characterizing the energy landscape of the CaO/MgO system a method known as 'Fair Phyllis' was used to generate databases of minima and transition states with the ultimate aim of producing a disconnectivity graph. [1] C.E. Mohn and S. Stolen, J. Chem. Phys. 123, 114104 (2005). [2] T. V. Bogdan, D. J. Wales, F. Calvo, J. Chem. Phys., 124, 044102, (2006) [3] F. Wang, D.P. Landau, Phys. Rev. Lett., 86, 2050, (2001) otherstatus: poster presented

2009-09-07T00:00:00Z