Pressure-induced second-order phase transition in fluorine. Issue 14 (23rd March 2023)

• Record Type: Journal Article
• Authors: Rech, Giovani L.; Martinotto, André L.; Zorzi, Janete E.; Perottoni, Cláudio A.
• Is Part Of: Physical chemistry chemical physics. Volume 25:Issue 14(2023)
• Page Start: 9935
• Page End: 9943
• Publication Date: 2023-03-23
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d2cp05635f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The relative stability between the crystal structure of α-F2, space group C 2/ c, and a hypothesized high-pressure phase, space group Cmce, was explored using Density Functional Theory and further assessed by Quantum Monte Carlo calculations. Abstract : The relative stability between the crystal structure of α-F2, space group C 2/ c, and a hypothesized high-pressure phase, space group Cmce, was explored using Density Functional Theory at the PBE0+D3(ABC)/TVZP level of theory and further assessed by Quantum Monte Carlo calculations. The analysis of the phonon dispersion spectra reveals that, at ambient pressure, besides the energy difference favoring the C 2/ c structure, the Cmce phase also presents a dynamical instability near the Γ -point, which disappears with increasing pressure. The unstable vibrational mode can be related to the absence of σ-holes in the fluorine molecule, which renders a repulsive head-to-head interaction between molecules, as opposed to heavier halogens, in which the presence of σ-holes stabilizes the orthogonal Cmce structure. The results show that the pressure-induced phase transition C 2/ c → Cmce is of second-order.