磷灰石晶体及表面基因的第一性原理计算

基于第一性原理的 MS软件 CASTEP模块，首先对磷灰石矿物晶胞进行了 几何优化，计算得到了其能带结构、态密度、Mulliken布居，然后建立并优化了3种不同（001）表面，分别 计算其表面能，并计算了磷灰石（001）低能面的差分电荷密度。结果表明：磷灰石晶体的禁带宽度为 5.657 eV，属于绝缘体 ，其能带主要分布在-38.5~-15.1 eV 之间。O3-Ca1 键布居值最小，是断裂概率较高的键，且 O3 的 2p 轨道在费米 能级附近电子密度贡献最大，易作为活性位点参加矿浆里的物理化学反应。相对于 PO₄终端面和 Ca1-Ca1 终端面， Ca1 终端面具有最低的表面能，性质最稳定，是自然界存在概率较高的表面。（001）表面的差分电荷密度分析表明 ，与 O3-Ca1 键相比，O3-Ca2 键共价性更强，键较难断裂，这与 Mulliken 键布居分析结果相符。磷灰石晶体和表 面的第一性原理计算结果可以为完善基因矿物加工数据库的建设和磷矿浮选药剂作用原理分析提供参考和指导。

First-principles Calculation of Fluorapatite Crystals and Surface Genes

CASTEP module based on the density functional theory（DFT） is used to optimize the structure of fluorapatite unite cell and obtained the band structure，density of states， and Mulliken population. Then 3 different fluorapatite （001）cleavage surfaces，the Ca1，Ca1-Ca1，PO4 termination，were established and optimized，and their surface energy were calculated respectively. The results show that fluorapatite is an insulator with a band gap of 5.657 eV，and its band is mainly distributed between -38.5 eV to -15.1 eV. O3-Ca1 bond has the smallest population value and is most easily broken of all bonds in the fluorapatite bulk. O3 contributes most near Fermi level，easy to participate in physical and chemical reactions as active site. The results also show that the Ca1 terminal surface have the lowest surface energy，become the most stable surface. Moreover，electron density difference plot of the optimum（001）surface shows that compared with O3-Ca1， O3-Ca2 shares more electrons，has stronger interactions，and are more difficult to break，which is consistent with the Mulliken population analysis result. The first-principles calculation results provide reference and guidance for the construction of a perfect genetic mineral processing database and the selection of a fluorapatite flotation process.