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本文把局域方法用于扩展Hubbard模型。在二阶近似下,计算了顺磁相的相关能、局域磁矩和由局域磁矩引起的极化。结果表明,尽管W不同,极化却总是反铁磁极化。当n=1,U较大时,相关能随W增加而变大。对给定的n和U,局域磁矩和反铁磁极化随W增加而变小,然而当n=1,U较大时或n较小时,W对二者影响不明显。In this paper, using the local approach, we calculated the correlation energy, the local moments and the polarisation around the local moments in paramagnetic phase up to second order in the extended Hubbard model. It is shown that the polarisation is always antiferro-magnetic for different values of W. The correlation energy increases with W increasing for n = 1 and large U. The local moments and the antiferromagnetic polarisation decrease with W increasing for fixed n and U. While the effect of W on both the local moments and the antiferromagnetic polarisation is not obvious for small n or for large U and n = 1.
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