Properties of defect centres on nanothick silica layers: an ab initio investigation

The structural, vibrational and electronic properties of the nanothick surfaces of mesoporous molecular sieves have been investigated at a microscopic level by ab-initio molecular dynamics. Simulations were performed on a series of 1-nm thick layers of a-SiO2 exhibiting different kinds of defects and on two reference samples of bulk amorphous silica. Our results show that the nanometre thickness of the mesoporous silica walls strictly influences the properties of the defect centres.