Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics.

ABSTRACT: The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238-270 K) and low-temperature (100-230 K) phases were studied in detail. In the temperature interval 230-238 K, a phase transition with rather low enthalpy (-1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of is

SUBMITTER: Volodin AD 

PROVIDER: S-EPMC9408834 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature