**************** The 21th., Lab Seminar *****************

Date: Thu, March 18, 2004  PM 4:00-

Place: No.616 Seminar room
　　　　　　 Graduate School of Information Science

Speaker: Hiromichi Nagao

Title: Hydrogen bonding in solid ammonia from ab initio calculations
　　　　　
Abstract:
 We have carried out ab initio simulations on the ambient 
pressure phase I of solid ammonia, and on the high-pressure 
phase IV. Our plane-wave psedopotential calculations yield 
very good agreement with existing structural data, lattice 
energies, and equations of state. We have also studied the 
tendency toward symmetrization of the hydrogen bonds at high
pressures and find that, unlike pure ice, this process should 
not occur at experimentally achievable pressures, i.e., <300 GPa. 
Moreover, our results show that ammonia IV does not contain 
a bifurcated hydrogen bond, as haspreviously been suggested.

**********************************************************