四面体键半导体合金LMTO能带的相干势近似计算

本文提出一种无须引入可调参数的基于LMTO能带的相干势近似(CPA)计算方法。在LMTO及其虚晶近似计算中,哈密顿矩阵的矩阵元计及原子球的d态,哈密顿矩阵对角化时忽略d带对s,p能带的影响,所得能带本征态便于构成适用于CPA计算的sp杂化正交轨道且能带结构较为合理。以Ga_1-xAl_xAs为例,论证这一方法在四面体键半导体合金中的应用。计算结果表明,其重要能带及相应带隙的弯曲参数的CPA修正值是合理的。 关键词：

A CPA CALCULATION OF THE LMTO BAND STRUCTURE FOR TETRAHEDRAL BOND SEMICONDUCTOR ALLOYS

A new approach for the CPA treatment of band structure of semiconductor alloys based on the LMTO-ASA-VCA method is suggested, in which no adjustable parameter is needed. In. order to construct a set of orthonormal sp-like hybrid orbitals from calcutated eigenstates and apply for CPA calculation, it is found that the following procedure is suitable: in the process of LMTO calculation and its VCA treatment, d states of atoms should be included in the matrix elememts, and d-band hybridization effect may be regarded as negligible for the secu-ler equation calculation. This method is illustrated with GaAlAs alloys. The results indicate that the CPA's calculation values of bowing parameters of bands and band-edges are quite reasonable.