Ab initio calculations predict a metal-insulator transition at zero temperature to occur in La4Ni3O8 at moderate pressures as a result of a pressure-induced spin-state transition. The spin-state transition that is seen at 105 K at ambient pressure from a low-temperature high-spin state to a high-temperature low-spin state has been observed to be shifted to lower temperatures as pressure is applied. From our calculations we find that a smaller unit cell volume favors the metallic low-spin state, which becomes more stable at 5 GPa. Similar physics should take place in the related compound La3Ni2O6, but on a different energy scale, which may account for why the transition has not been observed in this material.
@article{arxiv.1106.4828,
title = {Pressure-induced metal-insulator and spin-state transition in low-valence layered nickelates},
author = {Victor Pardo and Warren E. Pickett},
journal= {arXiv preprint arXiv:1106.4828},
year = {2015}
}