Theoretical study of lattice instabilities in YBa2Cu3

Abstract

We have performed a molecular dynamics simulation of the YBa2Cu3O.i structure under the constraints of the rigid-ion model. These simulations used a variety of charge states for the Cu ions and the 0 ions, and except for one case, the interionic potentials were obtained in an ab initio fashion. The results of these simulations showed that a lattice instability involving the Cu-0 chains existed. This instability was further investigated and it was shown that simple electronic screening is probably insufficient to stabilize the lattice. An instability of this nature provides a simple explanation of some experimentally observed phenomena.

Vibronic origins of highTc

“…In the case of YBCO, our molecular dynamics simulations (Billesbach et al, 1989) indicate that the nominal structure (from X-ray and neutron measurements) (Capponi, et al, 1987;You et al, 1987;Marsh et al, 1988;Williams et al, 1988) can never be other than metastable. Specifically, the oxygen chains along the b axis are under compression due to the fact that barium-oxygen distances in the layers of square pyramids above and below are too short.…”

Local dynamics ofYBa2Cu3Kristoffel1, Klopov2 1996Phys. Rev. B

“…A conclusion of possible O͑1͒ destabilization in the 123 system with the formation of zigzag chains has been obtained based on molecular dynamics calculations also in Ref. 19.…”

Combinative energy between two structural blocks and its correlation with superconductivity in Bi and Hg superconducting systems

“…We use ionic model to simplify this problem. Some authors [2][3][4][5][6][7][8] have demonstrated that the ionic model can be used to deal with the high-temperature superconductors. According to Pauling's rule, 9 it is reasonable to consider that the Bi-system superconductors are ionic compounds.…”