The Role of the Lone Pairs in Hydrogen Bonding

Tuesday, February 6 08:45-10:15
Maximum Probability Domains From Quantum Monte Carlo
Calculations
Anthony Scemama 1 , Michel Caffarel 1 , Andreas Savin 1
1 Laboratoire de Chimie et Physique Quantique, IRSAMC CNRS and Université Paul Sabatier, 118 route
de Narbonne, 31062 Toulouse Cedex, France 2 Laboratoire de Chimie Théorique, CNRS and Université
Paris Pierre et Marie Curie, Case 137, 4 place Jussieu, 75252 Paris Cedex 05, France
Although it would be tempting to associate the Lewis structures to the maxima of the squared wave
func- tion Èy È2 , we use domains of the three-dimensional space, which maximize the probability
of containing opposite-spin electron pairs. We find for simple systems (CH4, H Â2O, Ne, N2,
C2H2)domainsqualitativleycomparabletothoseobtainedwiththeelectronlocalizationfunction(ELF )orbylocaliz
and of the symmetric hydro- gen bond in FHF- . Furthermore, the presence of multiple solutions has an
analogy with resonant structures, as shown in the trans-bent structure of Si2H2.
Correlated wave functions were used (MCSCF or Slater-Jastrow) in the Variational Quantum Monte
Carlo framework.
10