A new type of Bloch–Wilson metal–insulator transition in liquid Se near the critical point and under pressure

Abstract The mechanism of a metal–insulator (MI) transition due to weakened bonds that we have previously discovered is shown to be applied not only to supercritical liquid Se but also to liquid Se under high pressure as well as to the explanation of the electronic properties in group IV elements and group III–V compounds. We regard our mechanism as a kind of Bloch–Wilson transition since the insulator-to-metal (I-to-M) transition takes place by band overlap. For the traditional Bloch–Wilson I-to-M transition (which we refer to as `Type I'), the band overlap is brought about by band broadening because of volume contraction . In contrast, the band overlap in our mechanism (which we refer to as `Type II') is caused by the decrease of the energy splitting between the bonding and antibonding band accompanying volume expansion , which is opposite to the `Type I' mechanism. In this sense, the mechanism underlying our discovery is a completely new type of Bloch–Wilson MI transition.