Microscopic instanton dynamics in molecules and crystals. Tunneling in NH3
Katsnel'son M. I. , Antropov V. P. , Van Schilfgaarde M. , Harman B. N.
A method is proposed for constructing a systematic microscopic description of tunneling processes in molecules and solids. The method is based on the quasiclassical approximation (introduction of instantons) for the nuclear variables and a first-principles calculation of the electronic energy. The inverse splitting of the ground state in NH3 molecules is calculated. © J 995 American institute of Physics.