State key Laboratory for Mechanical behavior of Materials, Xi’an Jiaotong Unversity; SMRC, Northwest Institute for Nonferrous Metal Research; Xi’an University of Architecture and Technology; Xi’an Aeronautical University
In this paper, the Partial Density of States (PDOS) of each element in doped Bi-2212 high temperature superconductor and H2S under high pressure is calculated by the first principle. According to the calculation results, we analysis the phenomenon that the critical temperature (Tc) of high temperature superconductor (HTS) Bi-2212 varies with doping content changing. When the Bi-2212 doping content is optimal, the electron energy is near the superconducting constrain gap, also the cohesive energy that the Cooper Pair electrons becoming needed is decreasing, so these electrons can turn into the superconducting cooper pairs more easily under the optimal content. In addition, with the optimal doping content, the densities of the superconductive electronics near Fermi surface increase to the maximum, which causes the number of becoming Cooper Pair electrons is increasing. Base on the two factors discussing above, the electrons can be induced to the superconducting electrons under higher temperature, thus the transition temperature of Bi-2212 increases. Last, this paper also discussed the calculation of the H2S under high pressure, it is known from the calculating results that the bond between the atoms can be destroyed because of the lattice contraction under high pressure. We speculate that the distribution of the electrons does not satisfy the Pauli Exclusion Principle under high pressure, but in a form liking "crowded". When the H2S is loaded voltage under high pressure, the "crowded" electrons can move as the carrier and form the electronic current, in the processing, due to the collision does not occur between electrons, thus the variation of the electron momentum is zero, so the H2S shows the zero resistance phenomenon in the Room temperature under high pressure.