Molecular Dynamics Study of a New Metastable Allotropic Crystalline Form of Gallium—Supertetrahedral Gallium

Document Type

Article

Journal/Book Title

Journal of Computational Chemistry

Publication Date

4-8-2019

Publisher

John Wiley & Sons, Inc

Award Number

NSF, Division of Chemistry (CHE) 1664379

Funder

NSF, Division of Chemistry (CHE)

Volume

40

Issue

20

First Page

1861

Last Page

1865

Abstract

A new metastable crystalline form of gallium has been computationally designed using density functional calculations with imposing periodic boundary conditions. The geometric and electronic structures of the predicted new allotrope were calculated on the basis of a diamond lattice in which all carbon atoms are replaced by gallium Ga4 tetrahedra. This form does not have any imaginary phonons, thus it is a metastable crystalline form of gallium. The new form of gallium is a metal and shows high plasticity and low‐melting temperature. Molecular dynamics simulations show that this form of gallium will melt at about 273 K with a sharp increase in temperature in the system during the melting process from 273 to 1800 K. This melting process is very different from conventional melting, where temperature stays the same until complete melting. That unusual melting can be explained by the fact that supertetrahedral gallium is a metastable structure that has an excess of strain energy released during melting. If made this new material may find many useful applications as a new low density metal with stored internal energy.

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