TEMPERATURE-DEPENDENT 2ND-ORDER SUSCEPTIBILITY IN BATIO3

Using the semiclassical density matrix approach, temperature dependent second-order susceptibility chi((2))(T) has been studied analytically in ferroelectric BaTiO3 crystal. The transitions between oxygen 2p an d titanium 3d states have been accounted. The role of many-body effect s is incorporated qualitatively by assuming the existence of local fie lds, which cause parity indefiniteness in the system. The second order susceptibility is found to decrease rapidly near the transition tempe rature. (C) 1998 Elsevier Science Ltd.