面心立方金属的空穴松弛能和空穴形成能的计算

本文利用纯金属的Morse势计算了五种面心立方金属(Pb,Ag,Ni,Cu,Al)的空穴松弛能和空穴形成能。计算松弛能时,除了考虑原子重新分布外,还特别考虑了电子云重新分布所引起的效应。如此求得的松弛能分别为1.27—1.36,>1.73,1.93—2.29,1.52—1.84,>1.09eV,比没有考虑电子云重新分布求得的松弛能大一个多电子伏。这表明电子云重新分布对松弛能的贡献是很重要的。由于求得了比较合理的松弛能,因而找到了一种模型比较简单,充分考虑到松弛效应的、适合于计算所有立方金属空穴形成能的方法。最后,求得上述金属的空穴形成能分别为0.64—0.74,<1.22,1.78—2.15,1.52—1.85,<1.67eV,比实验值大一些;它给出了上述实际金属的合理的理论上限值。

A THEORETICAL CALCULATION OF THE ENERGIES OF VACANCY RELAXATION AND VACANCY FORMATION IN THE FACE-CENTRED CUBIC METALS

In the present paper, the energies of vacancy relaxation and vacancy formation of the face-centred cubic metals (lead, silver, nikel, copper, and aluminium) are calculated by using the idea of metallic bond and the Morse potential of pure metals.In the calculation of relaxation energy, both the atomic and the electronic redistribution are considered. The energies of vacancy relaxation calculated by using the present method are 1.27-1.36,>1.73, 1.93-2.29, 1.52-1.84, and >1.09 eV respectively. These results are more reasonable than those obtained without taking into account the electronic redistribution. These results indicate that the contribution of electronic redistribution to the effect of relaxation is very important.The formation energies of vacancy calculated by using the present method for the five metals mentioned above are 0.64-0.74, <1.22, 1.78-2.15, 1.52-1.85, and <1.67 eV respectively. They are larger than the experimental values by a fraction of one electron volt. This result gives a reasonable theoretical upper limit to the formation energy of vacancy.