Density functional study on the thermal stability of RMn2O5 (R=Bi, Y, Gd, Pr or Sm)

Abstract

High throughput computational screening methods based on density functional theory has been an extraordinary success, but calculating the thermal stability of heavy and rare earth evolved transition metal oxide compounds still remain a challenge. In this work, by using a mixed GGA and GGA+U method, we have investigated the heavy and rare earth elements effect on predicting thermal stability of RMn2O5 (R=Bi, Y, Gd, Pr or Sm) compounds. The temperature phase diagram constructed from the DFT simulation without R site correction are demonstrate to show good prediction on the decomposition reactions, but the predicted temperature gives an underestimation comparing to the existing experimental data. The d/f orbital charge of R site elements indicate uncorrected rare earth elements could induce certain amount of simulation inaccuracy similar to transition metal elements and the amount of charges in these orbitals shows liner relationship with the prediction error. Our GGA+U correction results demonstrate that further correction on R site elements (same to transition metal elements) could effectively improve the accuracy of thermal stability prediction without introducing other high computational cost methods.