title: Crystal-liquid phase relations in silicon at negative pressure.
abstract: The stable and metastable melting relations for silicon in the diamond and Si136 clathrate-II structures at positive and negative pressures are calculated by molecular dynamics computer simulation. The simulated liquid and crystalline clathrates undergo cavitation at approximately -3 and -12 GPa. Between these limits a stretched crystal would transform directly to gas in response to a mechanical instability. Most importantly, the clathrate-II crystal becomes thermodynamically stable over the diamond at negative pressure below -1 GPa at the melting point. Si136 should then crystallize from a slightly stretched liquid, which would have the same volume as a diamond-structure crystal.
authors.affiliation: Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Wilson
authors.forename: Paul F
authors.initials: PF
authors.lastname: McMillan