Accuracy of buffered-force QM/MM simulations of silica
| Autor: | James R. Kermode, Alessandro De Vita, Lucio Colombi Ciacchi, Gianpietro Moras, Anke Peguiron |
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| Přispěvatelé: | Publica, Peguiron, Anke, Colombi Ciacchi, Lucio, DE VITA, Alessandro, Kermode, James R, Moras, Gianpietro |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Length scale
first principles General Physics and Astronomy Boundary (topology) 01 natural sciences Molecular physics QM/MM Molecular dynamics Quantum mechanics 0103 physical sciences Point (geometry) QD materials modelling Physical and Theoretical Chemistry chemical bond 010306 general physics QC Coupling 010304 chemical physics first principle Chemistry molecular dynamic Fracture mechanics vacancies electrostatics quartz molecular dynamics embedding techniques silica Density of states |
| ISSN: | 0021-9606 |
| Popis: | We report comparisons between energy-based quantum mechanics/molecular mechanics (QM/MM) and buffered force-based QM/MM simulations in silica. Local quantities-such as density of states, charges, forces, and geometries-calculated with both QM/MM approaches are compared to the results of full QM simulations. We find the length scale over which forces computed using a finite QM region converge to reference values obtained in full quantum-mechanical calculations is similar to 10 angstrom rather than the similar to 5 angstrom previously reported for covalent materials such silicon. Electrostatic embedding of the QM region in the surrounding classical point charges gives only a minor contribution to the force convergence. While the energy-based approach provides accurate results in geometry optimizations of point defects, we find that the removal of large force errors at the QM/MM boundary provided by the buffered force-based scheme is necessary for accurate constrained geometry optimizations where Si-O bonds are elongated and for finite-temperature molecular dynamics simulations of crack propagation. Moreover, the buffered approach allows for more flexibility, since special-purpose QM/MM coupling terms that link QM and MM atoms are not required and the region that is treated at the QM level can be adaptively redefined during the course of a dynamical simulation. |
| Databáze: | OpenAIRE |
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