Crystal Distortion and Electric and Magnetic Transition in VO2

The semiconductor to metal transition in VO 2 is discussed in connection with the crystal distortion on the basis of a simplified one-dimensional model. It is shown that a localized electron state forming ion pairs will be stabilized at low temperatures when the transfer energy makes a sudden increase for a small contraction of ionic distance. The occurrence of the semiconductor to metal transition is explained by the stabilization of the delocalized state at high temperatures due to the excitation of electrons from the bonding to the antibonding state in each ion pair.