We have investigated the volume collapse occurring in LaMnO3 unit cell using the anisotropic Potts model modified by two types of anisotropic interactions which has been used to study the change of Mn-O bonds lengths as function of temperature. The bond lengths are related to the occupation of the orbits. The lattice parameters and the distortion modes have been investigated as well. We have shown that the collapse is due to the change of Mn-O bonds lengths change as the temperature is raised through the transition. It has been shown that all the parameters studied here decrease with increasing temperature in a narrow temperature range below TJT, and then undergoes a collapse at TJT. These results are in a good agreement with the published experimental results.
تحميل البحث