Thermodynamical Behaviour of PdSe2 while Subjected Isothermally to High Pressure – Volumetric Level Analysis

We study thermodynamically the behaviour of PdSe2 while subjected to high pressure under isothermal conditions. The present paper discusses the volumetric-level calculations and results. Experiments under two certain temperature levels are performed: 20oC and 300oC. Calculations and analyses are done according to the method for thermodynamical analysis developed by us in [1]. We detected the order of phase transition from PdS2 structure type to pyrite one to be first order notwithstanding the temperature level. Values of transition pressure were found to be 12.24 GPa and 9.785 GPa at 20oC and 300oC, respectively. Adjusted entropy generation during compression was calculated aiming to study stability of treated compound. Influence of compression temperature level was analysed, as well as duration of pressure plateaux.

The Order of Phase Transition of Solvable DNA Melting Models

The phase transition of DNA molecules is studied in an exactly solvable formalism with the Morse and Deng–Fan potentials for the interstrand hydrogen bonds of nucleotide base pairs. It is shown that although the two potentials have different short-range behaviors, the thermodynamic quantities of the DNA system in these potentials enjoy the same scaling laws with the associated critical exponents, which are explicitly calculated. These exactly solvable DNA models are shown to exhibit a phase transition of the second order and the results of the analysis agree with previous studies.

MORE ON PHASE STRUCTURE OF NONLOCAL 2D GENERALIZED YANG–MILLS THEORIES (nlgYM2's)

We study the phase structure of nonlocal two-dimensional generalized Yang–Mills theories (nlgYM2) and it is shown that all order of ϕ2k model of these theories has phase transition only on compact manifold with g = 0 (on sphere), and the order of phase transition is 3. Also it is shown that the [Formula: see text] model of nlgYM2 has third order phase transition on any compact manifold with [Formula: see text], and has no phase transition on the sphere.