Publication No.22



A. Stashans, H. Pinto. Hole polarons in pure BaTiO3 studied 
by computer modeling - Int. J. Quant. Chem., 2000, Vol. 79, 
p. 358-366. 

Abstract:
	Self-trapped hole polarons in technologically important perovskite-type 
ceramic of BaTiO3 have been modeled by means of the quantum-chemical method 
modified for crystal calculations. The computations are carried out in the SCF 
manner using the embedded molecular cluster model. The spatial configuration of 
a hole polaron, displacement of defect-surrounding atoms, wave functions of the 
polaron ground and excited states are obtained and analyzed. The probability of 
spontaneous hole self-trapping is estimated in the perfect lattice of BaTiO3 crystal 
by calculating the value of hole self-trapping energy as a difference of the atomic 
relaxation energy and the hole localization energy. This value is found to be 
negative, -1.49 eV, which demonstrates the preference of the self-trapped polaron 
state. The calculated polaron absorption energy, 0.5 eV, is discussed in light of 
the available experimental data.




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