Calculated elastic and electronic properties of MgB2 at high pressures

The effect of high pressure on structural and electronic properties of the novel superconductor MgB2 has been calculated using the full-potential line arized augmented-plane-wave method. Despite the layered crystal structure o f MgB2 nearly isotropic compression (bulk modulus B-o = 140.1(6) GPa) is fo und with only a 1.2% decrease of the c/a ratio at 10 GPa. The effect of pre ssure on the critical temperature has been estimated on the basis of BCS th eory and good agreement with experimental data is found. Our results sugges t that it is a combination of increasing phonon frequency and decreasing el ectronic density of states at the Fermi level which leads to the observed d ecrease of the critical temperature under pressure. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.