First-principles Study Of Physical Properties Of Liquid Benzene Under High Temperature And High Pressure

Researches on metal transition of hydrocarbon under extreme condition is a question of scientific interest.Benzene is the best simple aromatic compound.Exploring properties of liquid benzene under high pressure and high temperature has important scientific significance for researching on other aromatic compounds under extreme condition.In this paper,the influence of thermodynamic properties of temperature and pressure of fluid benzene are calculated and analyzed through the molecular dynamics simulation based on density functional theory,obtaining the equation of state of liquid benzene and analyzing the change of Changes of chemical composition in different temperature and the same density.There is more detailed analysis of the conductivity of benzene under high temperature and high pressure.Finally,the existence of liquid metal benzene was confirmed.The results of our research in this paper is mainly the following several aspects:1.The molecular dynamics simulation based on density functional theory was used to study equation of liquid benzene under shocked comprehension.The density is range from 1.6-2.4 g/cm3 and temperature is from 1500-5000 K,corresponding to range of the pressure is between 11 GPa-75 GPa.Every isochore line has characteristic which is the pressure area of stagnation or lower except ?=1.6 g/cm3.The temperature of that area decreases,and the temperature range is narrow with the increase of density with the pressure increasing.2.Analysis of the structural change of 1.6 g/cm3 shows that the pressure of benzene decomposition is in good agreement with the calculated results of previous.We observed change of structures through the structure before and after(/)0V?p ?T ? area.For 2.4 g/cm3 and 1.8 g/cm3,the pair correlation functions(PCF)of the different temperature are calculated,The PCF intuitively reflects the chemical decomposition process.3.Through analysis on the configurations and the pair correlation functions can obtained: while the pressure is small,especially at the beginning of the decomposition of benzene,there are a small amount of polycyclic aromatic hydrocarbons and smaller hydrocarbon molecules in system.There is mainly composed of C-C and C-H bond rupture to form some long carbon chain and a small amount of hydrogen with the pressure increasing in the system.C-C and hydrogen bond convert to fracture shorter carbon chain and carbon atoms,and hydrogen will be partially dissociates into hydrogen atoms under higher pressure.4.Calculate the band gap of the sample structures.It is found that the phase transition of liquid benzene is near the lowest point of the sudden decrease of the pressure in the same volume by the temperature-band gap diagram.At the same time,partial density of states(PDOS)of three 2.4 g/cm3 were calculated.Analysis of PDOS can find the conductive structure in the system is mainly carbon that is on shorter carbon chain and atoms,while hydrogen atoms also contribute to conducting.Finally,we give the corresponding phase diagram of benzene.