Quantum chemical study and low-temperature calorimetry of phase transition V4S9Br4

摘要

The phase transition in a mixed-valence tetranuclear compound V4S9Br4 was studied by DFT calculations and low-temperature high-precision calorimetry. According to DFT data, the phase transition of the low-temperature modification may be accompanied by C-4v -> C-2v symmetry lowering and electron spin pairing. A weak exchange-correlation interaction discovered between mu 4-S2- and S2- ions in V4S9Br4 may play an important part in multicentered interactions. Experimental calorimetric data show that the phase transition is a displacive phase transformation. (C) 2008 Elsevier Inc. All rights reserved.