A simple tight-binding model description of the conduction band of the Kondo insulator YbB12

It is shown that the conduction band of typical Kondo insulator YbB12 can be expressed rather well by a simple tight-binding model of 5dε orbitals on Yb. The (ddσ) overlapping integral is considered to be produced by the hopping through B12 clusters. The density of states is also calculated. If the mixing with the f-states is properly taken into account, this model can be a useful starting point for incorporating the strong correlation effect, and can consistently explain all the thermal, thermoelectric, transport and magnetic properties of YbB12