Electronic structure of RVO3 (R = La and Y): Effect of electron (U) and exchange (J) correlations

We have studied the influence of electron correlation energy (U) and exchange correlation energy (J) on the electronic structure of RVO3 (R = La and Y) compounds using all-electron full-potential linearized augmented plane wave method within density functional theory. Our calculated electronic band structure shows metallic character with generalized gradient approximation (GGA) formalism though LaVO3 and YVO3 are both known to be insulators with a band gap of 1.1 eV and 1.2 eV, respectively. Our GGA+U approach has succeeded in describing the correct ground state yielding insulating band structures for both LaVO3 and YVO3. However, this insulating ground state is obtained by adjusting the parameter, U to reproduce the correct experimental band gap. To determine the optimal U value for the onsite coulomb potential, we have performed a series of GGA+U calculations by varying the Ueff (difference between U and J) parameter keeping J fixed. We have also varied the exchange parameter J, (though not as strong as that of U) keeping Ueff fixed to see its influence on the band gaps of LaVO3 and YVO3 and it has been shown that both the U and J have great impact on the electronic structure of these two compounds.