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CPP: Chemische Physik und Polymerphysik
CPP 7: Computational Physics
CPP 7.4: Talk
Tuesday, March 25, 2003, 17:45–18:00, ZEU/160
Quantum-Monte-Carlo study of hydrogen bonded molecules — •A. Badinski1, C. Filippi2, M. Fuchs1, J. Ireta1, P. Kratzer1, and M. Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin — 2Instituut Lorentz for Theoretical Physics, Univ. Leiden
Hydrogen bonds play a key role in the structure and functionality of biomolecules. Density-functional theory (DFT) is a useful tool for describing such systems. Still, the accuracy of DFT is limited due to its in practice approximate account of exchange-correlation. Quantum-Monte-Carlo (QMC) calculations may help to identify and correct such shortcomings, even in larger systems where standard quantum chemical methods are impractical [1]. Using the Diffusion-QMC method we calculate three model systems with medium-weak H-bonds: Di-ammonium and formamide-water, where we examine the equilibrium states and proton transfer; formamide chains, where we address the H-bonds’ cooperativity for increasing chain lengths. Molecular structures, first computed by DFT, are carefully monitored. Our QMC results agree well with post Hartree-Fock quantum chemical data, especially for proton transfer energy barriers that DFT underestimates. − [1] C. Filippi, S.B. Healy, P. Kratzer, E. Pehlke, and M. Scheffler, Phys. Rev. Lett. 89, 166102 (2002).