Density-functional study of pressure-induced phase transitions and electronic properties of Zn 2 V 2 O 7 .

We report a study of the high-pressure behavior of the structural and electronic properties of Zn 2 V 2 O 7 by means of first-principle calculations using the CRYSTAL code. Three different approaches have been used, finding that the Becke-Lee-Yang-Parr functional is the one that best describes Zn 2 V 2 O 7 . The reported calculations contribute to the understanding of previous published experiments. They support the existence of three phase transitions for pressures smaller than 6 GPa. The crystal structure of the different high-pressure phases is reported. We have also made a systematic study of the electronic band-structure, determining the band-gap and its pressure dependence for the different polymorphs. The reported results are compared to previous experimental studies. All the polymorphs of Zn 2 V 2 O 7 have been found to have a wide band gap, with band-gap energies in the near-ultraviolet region of the electromagnetic spectrum.