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采用经验紧束缚理论，以类似闪锌矿结构的晶体模型模拟Ｇｅ＿ｘＳｉ＿（１－ｘ）合金，根据总能最小原则计算了Ｇｅ＿ｘＳｉ＿（１－ｘ）合金中的键长及点阵常数．同时以紧束缚方法计算了原子位置发生弛豫前后的电子能带结构，并与虚晶近似下的计算结果进行了比较．计算结果表明，Ｇｅ＿ｘＳｉ＿（１－ｘ）合金中的键长基本上与合金组分无关，各自接近于Ｇｅ，Ｓｉ晶体中的键长，与广延ｘ射线吸收精细结构（ＥＸＡＦＳ）测量结果符合得很好．原子位置的弛豫对合金的电子能带结构影响很小，对合金的电子能带结构起主要作用的是合金的化学组分无序．
The tight binding theory is used to simulate the Ge_xSi_ (1-x) alloy with a crystal model of sphalerite and the bond length and lattice constants in Ge_xSi_ (1-x) alloys are calculated according to the principle of the smallest total energy. At the same time, the electronic band structure before and after the relaxation of atomic position was calculated by the tight binding method, and the calculated results were compared with the virtual crystal approximation. The calculated results show that the bond lengths in Ge_xSi_ (1-x) alloys are basically independent of the alloy compositions and close to the bond lengths in Ge and Si crystals, respectively, which are in good agreement with the results of extended x-ray absorption fine structure (EXAFS) well. The relaxation of the atomic position has little effect on the electronic band structure of the alloy, and the main effect on the electronic band structure of the alloy is that the chemical composition of the alloy is disorderly.