2001/07/16 by Giovanni Jona-Lasinio, Carlo Presilla, Cristina Toninelli
Physics and Astronomy · #cond-mat #hep-th #physics.atom-ph #quant-ph
published as Fields Inst.Commun. 30 (2001) 207-217 · 10 pages, 1 figure
arxiv created 2001/07/16 · arxiv updated 2009/11/30
We propose a model to describe a gas of pyramidal molecules interacting via dipole-dipole interactions. A cooperative effect induced by the interaction modifies the tunneling properties between the classical equilibrium configurations of the single molecule. The model suggests that, for sufficiently high gas density, the molecules become localized in these classical configurations. On this basis it is possible to explain the shift and the disappearance of the inversion line observed upon increase of the pressure in a gas of ammonia or deuterated ammonia. The same mechanism also accounts for the presence of stable optical activity of certain pyramidal molecules. We discuss the concept of environment induced superselection rule which has been invoked in connection with this problem.