The α - β (fcc-hcp) phase transition temperature under pressure can be investigated theoretically by combining the self-consistent field method and the statistical moment method and only the statistical moment method which was developed by the authors. Theoretical results are applied to N2 and CO molecular cryocrystals and our calculated results are compared with the experimental data and other calculations. | JOURNAL OF SCIENCE OF HNUE Mathematical and Physical Sci. 2014 Vol. 59 No. 7 pp. 93-100 This paper is available online at http STRUCTURAL PHASE TRANSITION TEMPERATURE OF N2 AND CO MOLECULAR CRYOCRYSTALS UNDER PRESSURE Nguyen Quang Hoc1 Bui Duc Tinh1 Dinh Quang Vinh1 and Nguyen Duc Hien2 1 Faculty of Physics Hanoi National University of Education 2 Mac Dinh Chi Secondary School Chu Pah District Gia Lai Province Abstract. The α - β fcc-hcp phase transition temperature under pressure can be investigated theoretically by combining the self-consistent field method and the statistical moment method and only the statistical moment method which was developed by the authors. Theoretical results are applied to N2 and CO molecular cryocrystals and our calculated results are compared with the experimental data and other calculations. Keywords Self-consistent field statistical moment molecular cryocrystal. 1. Introduction Electronic transitions lie at the heart of many high-pressure phenomena including structural stability and metallization 1 . Such changes in the underlying electronic structure drive concomitant sequences of structural phase transitions and there has recently been intense interest in such changes for the alkali and alkaline earth metals. He and Xe transform from face-centered cubic fcc structures to hexagonal close-packed hcp structures at high pressures but corresponding transitions have not been reported for Ne Ar or Kr. The properties of rare-gas solids at high pressures are of fundamental interest because they provide an ideal system due to their closed-shell electronic configurations allowing fruitful comparison between experiment and theory. The polymorphous transformation is the phase transition between the different configurations of a crystal. Because this transformation temperature is smaller than the melting temperature in order to investigate it Kotenok 2 applied the one-particle distribution method OPDM of Bazarov 3 in the .
