水分子与白云石(104)表面相互作用的第一性原理研究

DFT Simulation on Interaction of H_(2)O Molecules with Dolomite(104)Surface

为了研究白云石(104)表面吸附水分子的水化结构,利用密度泛函理论(DFT)模拟了单个及多层水分子在白云石表面的吸附。结果表明,白云石表面的Ca、Mg位点可以与水形成(Ca/Mg)—O_(w)键,主要是Ca3s3d轨道、Mg3s2p轨道及与O2p轨道作用,水分子在白云石表面Ca位点的吸附作用强于Mg位点。多层水分子在白云石表面吸附时,水分子层结构发生了明显分层,最靠近白云石表面的水分子层中,水分子在Ca、Mg位点上有序排列,平均吸附能为-74.35kJ/mol;随着距离的增加,矿物表面与水分子间相互作用逐渐减弱,水分子吸附能减小。

To investigate the hydration structure of H_(2)O molecules adsorbed on dolomite(104)surface,single and multilayer H_(2)O molecules on dolomite surface were performed by density functional theory(DFT).The results showed that the Ca and Mg sites on dolomite surface could form(Ca/Mg)-O_(w) bonds with H_(2)O,their overlap is mainly contributed by the Ca 3s3d,Mg 3s2p and O 2p states.The adsorption of H_(2)O molecule on Ca site was stronger than that on Mg site.And the adsorption of multi layer H_(2)O molecules on dolomite surface,H_(2)O layer structure has obvious stratification.For the H_(2)O molecule layer closest to dolomite surface,H_(2)O molecules were arranged in order at the Ca and Mg sites,and average adsorption energy was-74.35 kJ/mol.With the increase of distance,the interaction between mineral surface and water molecules g radually weakens,and adsorption energy of water molecules decreases.