科研之友
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摘要
It is well accepted that the virtual crystal approximation provides an effective method for studying solid solutions and alloys from first principles. Here we propose another approach based on a well designed averaging of the pseudo-wavefunctions. As from physical and numerical considerations there is a subtle arbitrariness in constructing the Kleinman-Bylander pseudopotential, we can construct the orthonormalized pseudo-wavefunctions as well as pseudopotentials of the virtual atom by averaging. It is proved that this extended averaging approach can provide reasonable properties for heterovalent solid solutions, and has the advantage of great simplicity. Our results for the perovskite ferroelectrics (1-x) BiScO3-xPbTiO(3) satisfy Vegard's law well as regards the cubic lattice constants and display improved values as regards the structural and electrical properties compared with a previous work (I (n) over tilde iguez et al 2003 Phys. Rev. B 67 224107).
- 出版日期2007-8-1
