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

The band structure calculations of perovskite transition metal compoun d LaRhO3 performed using 'tight binding linear muffin tin orbital' (TB -LMTO) method within local density approximation (LDA) under ambient a nd high pressures are reported here. Our calculations are able to succ essfully 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 e nables 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 (C T) insulator which is in agreement with the recent experimental observ ations whereas LaRhO3 is a conventional band insulator. Further, the e quilibrium lattice constant, bulk modulus, its first derivative, and m etallization volume obtained from the total energy calculations for ex panded and reduced cell volumes are also reported for LaRhO3.