ELECTRONIC-STRUCTURE AND THE METAL-INSULATOR-TRANSITION IN LNNIO3 (LN=LA, PR, ND, SM AND HO) - BAND-STRUCTURE RESULTS

We report detailed band structure results on the series LnNiO3 with Ln = La, Pr, Nd, Sm and Ho. LaNiO3 is shown to be a pd metal, expected t o be close to localization due to correlation effects; the other four compounds are suggested to be covalent insulators. There is a systemat ic reduction in the bandwidths with increasing atomic number of the ra re-earth ion. Using a tight-binding analysis of the ab initio results, the reduction in the bandwidth is related to the changes in the inter cluster hopping interaction strengths arising from the structural chan ges driven by the lanthanide contraction across the series.