UCL logo

UCL Discovery

UCL home » Library Services » Electronic resources » UCL Discovery

High pressure ionic and molecular crystals of ammonia monohydrate within density functional theory.

Griffiths, GI; Misquitta, AJ; Fortes, AD; Pickard, CJ; Needs, RJ; (2012) High pressure ionic and molecular crystals of ammonia monohydrate within density functional theory. J Chem Phys , 137 (6) 064506 - ?. 10.1063/1.4737887.

Full text not available from this repository.

Abstract

A combination of first-principles density functional theory calculations and a search over structures is used to predict the stability of a proton-transfer modification of ammonia monohydrate with space group P4∕nmm. The phase diagram is calculated with the Perdew-Burke-Ernzerhof (PBE) density functional, and the effects of a semi-empirical dispersion correction, zero point motion, and finite temperature are investigated. Comparison with MP2 and coupled cluster calculations shows that the PBE functional over-stabilizes proton transfer phases because too much electronic charge moves with the proton. This over-binding is partially corrected by using the PBE0 hybrid exchange-correlation functional, which increases the enthalpy of P4∕nmm by about 0.6 eV per formula unit relative to phase I of ammonia monohydrate and shifts the transition to the proton transfer phase from the PBE pressure of 2.8 GPa to about 10 GPa. This is consistent with experiment as proton transfer phases have not been observed at pressures up to ∼9 GPa, while higher pressures have not yet been explored experimentally.

Type: Article
Title: High pressure ionic and molecular crystals of ammonia monohydrate within density functional theory.
Location: United States
DOI: 10.1063/1.4737887
Language: English
UCL classification: UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy
URI: http://discovery.ucl.ac.uk/id/eprint/1338715
Downloads since deposit
0Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item