Ab initio MO study on hydrogen release from surface of lithium silicate

Chemical nature of hydrogen on the lithium silicate and Al-doped lithium silicate surfaces was investigated with ab initio molecular orbital calculations. From the results of calculations, the charge distributions and proton affinity (PA) were obtained for the model clusters H4-xSiO4Lix and H7-xSiAlO7Lix (x = 0 and 1). It was shown by the calculation that the ionicity of surface hydrogen is strengthened by the interaction of Al atom to surface oxygen, while weakened by Li ion coordinated to nonbridging oxygen. Also, PA values decrease with increase in the ionicity of the surface hydrogen. (orig.)