From ab initio quantum chemistry to molecular dynamics: The delicate case of hydrogen bonding in ammonia

By A. Daniel Boese, A. Chandra, Jan M. L. Martin, Dominik Marx. 2003

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The ammonia dimer (NH3)2 has been investigated using high-level ab initio quantum chemistry methods and density functional theory. The structure and energetics of important isomers are obtained to unprecedented accuracy without resorting to experiment. The global minimum of eclipsed Cs symmetry is characterized by a significantly bent hydrogen bond which deviates from linearity by as much as ≈20°. In addition, the so-called cyclic C2h structure, resulting from further bending which leads to two equivalent “hydrogen bonding contacts,” is extremely close in energy on an overall flat potential energy surface. It is demonstrated that none of the currently available [generalized gradient approximation (GGA), meta-GGA, and hybrid] density functionals satisfactorily describe the structure and relative energies of this nonlinear hydrogen bond. We present a novel density functional, HCTH/407+, which is designed to describe this sort of hydrogen bond quantitatively on the level of the dimer, contrary to, e.g., the ...

Subfields: Atomic and Molecular Physics, and Optics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/054e1947c38637f286a8e0215011997e94a00d1b