Convergence of the many-body expansion of interaction potentials: From van der Waals to covalent and metallic systems
- Centre of Theoretical Chemistry, Physics and Institute of Advanced Studies and Institute of Fundamental Sciences, Massey University (Auckland Campus), Private Bag 102904, North Shore MSC, Auckland (New Zealand)
The many-body expansion of the interaction potential between atoms and molecules is analyzed in detail for different types of interactions involving up to seven atoms. Elementary clusters of Ar, Na, Si, and, in particular, Au are studied, using first-principles wave-function- and density-functional-based methods to obtain the individual n-body contributions to the interaction energies. With increasing atom number the many-body expansion converges rapidly only for long-range weak interactions. Large oscillatory behavior is observed for other types of interactions. This is consistent with the fact that Au clusters up to a certain size prefer planar structures over the more compact three-dimensional Lennard-Jones-type structures. Several Au model potentials and semiempirical PM6 theory are investigated for their ability to reproduce the quantum results. We further investigate small water clusters as prototypes of hydrogen-bonded systems. Here, the many-body expansion converges rapidly, reflecting the localized nature of the hydrogen bond and justifying the use of two-body potentials to describe water-water interactions. The question of whether electron correlation contributions can be successfully modeled by a many-body interaction potential is also addressed.
- OSTI ID:
- 21011247
- Journal Information:
- Physical Review. A, Vol. 76, Issue 1; Other Information: DOI: 10.1103/PhysRevA.76.013202; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ARGON
ATOM-MOLECULE COLLISIONS
ATOMIC CLUSTERS
ATOMS
COVALENCE
DENSITY FUNCTIONAL METHOD
ELECTRON CORRELATION
EXPANSION
GOLD
LENNARD-JONES POTENTIAL
MOLECULAR STRUCTURE
MOLECULES
SILICON
SODIUM
THREE-DIMENSIONAL CALCULATIONS
TWO-BODY PROBLEM
VAN DER WAALS FORCES
WATER
WAVE FUNCTIONS
WEAK INTERACTIONS