INSULATOR-TO-METAL TRANSITION IN LARHO3 UNDER HIGH-PRESSURE

The band structure calculations of perovskite transition metal compound LaRhO3 performed using 'tight binding linear muffin tin orbital' (TB-LMTO) method within local density approximation (LDA) under ambient and high pressures are reported here. Our calculations are able to successfully explain the insulating nature of the system and the insulator-to-metal transition (IMT) is observed for the reduced volume of 0.90. The first electronic structure calculation reported here for LaRhO3 enables us to compare it with that of LaCoO3 which brings out the role played by the d bands. These studies lead to distinguish between these two insulating systems and LaCoO3 is found to be a charge transfer (CT) insulator which is in agreement with the recent experimental observations whereas LaRhO3 is a conventional band insulator. Further, the equilibrium lattice constant, bulk modulus, its first derivative, and metallization volume obtained from the total energy calculations for expanded and reduced cell volumes are also reported for LaRhO3.