A Semiclassical Model for Molecular Localization in Ammonia

TL;DR

This paper presents a semiclassical model explaining how increased pressure induces localization in ammonia molecules by modifying tunneling dynamics, and it analyzes the pressure-dependent decrease in inversion line frequency.

Contribution

It introduces a semiclassical approach to model environment-induced localization in pyramidal molecules like ammonia, linking pressure effects to tunneling suppression.

Findings

High pressure leads to molecular localization in ammonia.

The model explains the decrease in inversion line frequency with pressure.

Localization occurs when interactions dominate tunneling dynamics.

Abstract

The pedagogic two stste system of the ammonia molecule is used to illustrate the phenomenon of environment induced molecular localization in pyramidal molecules. A semiclassical model is used to describe a gas of pyramidal molecules interacting via hard ball collisions. This modifies the tunnelling dynamics between the classical equilibrium configurations of an isolated molecule. For sufficiently high pressures, the model explains molecular localization in these classical configurations. The decrease in the inversion line frequency of ammonia, noted upon increase in pressure, is also studied.