绿松石呈色的晶体场理论计算

Calculation of crystal field theory on turquoise color forming

绿松石中Cu2+电子组态为3d9,为中心对称配位八面体,配位体为4个OH-和2个H2O,在晶体场作用下,五重简并的d轨道分裂为5个能量不同的轨道,dx2-y2为基态,其余为激发态,依跃迁选律,从基态到四个激发态的跃迁为自旋允许跃迁,从而形成了铜离子吸收光谱的4条谱带。前人对绿松石中Cu2+晶体场势能计算时,个别系数有误,笔者进行了修改,并补充了部分角度函数的积分值,从而使结果得到了改进,计算谱带位置与实测可见光吸收光谱谱带位置十分接近。在进行晶体场势能计算时,角度函数积分值是非常重要的,以往的资料只是直接给出了部分积分值,这在计算低对称配位八面体晶体场势能时是不够的,这次重新计算了所有可能的角度函数积分值,对各种对称下配位八面体晶体场能量的计算提供了可能。

The electron fabric of Cu^(2+) in turquoise is 3d^9, Cu^(2+) and its ligands,four OH^- and two H_2O,constitute centrosymmetric coordination octahedron.In crystal field,d-trajectrories of five-superposition divide into five orbits which have various energy. d_(x^2-y^2)is datum state,and the others are excitation states.According to transition select formula,the transitions from datum state to four excitation states are self-spin permitted transitions.Therefore,four absorption spectrum bands of Cu^(2+) is formed.While predecessors calculated crystal field potential of Cu^(2+),some parameters were not correct.Now,we modify these parameters and supply partial anglar function calculus.So the result is improved.The calculated spectrum positions are close to those by measured.When calculating crystal field energy,angular function is very important.Old data only give partial calculus results,but it is very limited to those ores having low-symmetry coordination octahedron when calculate their crystal field energy.We re-calculate all of possible anglar function calculus,and this supplies possibility for crystal field calculation of coordination octahedron in all kinds of symmetry.