Applications of the generalized gradient approximation to ferroelectric perovskites

S. TINTE; M. G. STACHIOTTI; C. O. RODRIGUEZ; D. L. NOVIKOV; N. E. CHRISTENSEN

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 1998 vol. 58 p. 11959 - 11959

1098-0121

The Perdew-Burke-Ernzerhof generalized gradient approximation to the density functional theory is tested with respect to sensitivity to the choice of the value of the parameter κ, which is associated with the degree of localization of the exchange-correlation hole. A study of structural and dynamical properties of four selected ferroelectric perovskites is presented. The originally proposed value of κ=0.804 works well for some solids, whereas for the ABO3 perovskites it must be decreased in order to predict equilibrium lattice parameters in good agreement with experiments. The effects on the structural instabilities and zone center phonon modes are examined. The need of varying κ from one system to another reflects the fact that the localization of the exchange-correlation hole is system dependent, and the sensitivity of the structural properties to its actual value illustrates the necessity of finding a universal function for κ.