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本文中提出了一种介于实空间法(RS)和多层法(MS)之间的新方法——准实空间法(QRS)。在QRS法中大部分数值计算在实空间进行,只有当电子波函数φ的归一化值超过预定的阈值,如Σ|φ|2>1.01时,才转到傅氏空间进行低通滤波(LPF)和运算。在倒空间运算后,通过逆傅氏变换,运算仍然在实空间进行。本文详细研究了RS法发散的原因,并提出了QRS法,这种算法克服了RS法中的发散现象,又在不延长计算时间的前提下得到了和普遍采用的多层法相一致的计算结果。This paper reports a study of the quasi real space (QRS) method. It is an intermediate procedure between the real space (RS) and multislice (MS) methods. With this technique, most of the numerical calculations are done in real space except that the rormalization is imposed beyond some threshold value, for example ∑|Φ|2>1.01 where Φ is the wave function of the electron. It is also shown why truncation of the propagation operator eλε△ to second order in the RS method can lead to computational divergencies and how they can be avoided by using the QRS method. Finally, results calculated by the QRS method are compared with other existing slice methods. The QRS method gives results similar to the conventional MS calculation with competitive computational speed.







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