First-principles calculations of structural properties of NaNbO3

R. MACHADO; M. SEPLIARSKY; M. G. STACHIOTTI

FERROELECTRICS

TAYLOR & FRANCIS LTD

Año: 2011 p. 1 - 14

0015-0193

We present ab-initio total energy calculations for different structures of NaNbO3 at differentvolumes using two different exchange-correlation functionals: the Perdew and Wang versionof the local-density approximation (LDA) and the Wu and Cohen version of the generalizedgradient approximation (GGA-WC). We found that LDA not only underestimates the equilibriumvolume of the system but also predicts an incorrect ground state for this oxide. TheGGA-WC functional, on the other hand, significantly improves the equilibrium volume andprovides a relative phase stability in better agreement with experiments. We then use theGGA to investigate the presence of structural instabilities as a function of volume in order toprovide insights for the understanding of the structural behavior of K1-xNaxNbO3 solid solutions.