A linear scaling of the number of nonzero integrals in extended systems calculations and the solution of the difficult cutoff threshold problems in the integral evaluation of periodic HF computations could be solved by the usage of orbitals with a finite extension. The present work proposes the usage of Box orbitals, defined inside spheres centered on the nuclei. Preliminary tests on small systems (atoms and H-2(+)) were performed. The results ale very encouraging, since, in most cases, the Box orbitals give better results (giving results of equivalent quality in the worse cases) than do the classical Gaussian orbitals. No spurious effects were encountered. (C) 1997 John Wiley & Sons, Inc. [References: 12]
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机译：扩展系统计算中非零积分数量的线性缩放和周期性HF计算的积分评估中难于解决的临界阈值问题，可以通过使用有限扩展的轨道来解决。本工作提出了Box轨道的用法，Box轨道定义在以原子核为中心的球形内部。在小型系统（原子和H-2（+））上进行了初步测试。结果非常令人鼓舞，因为在大多数情况下，Box轨道比经典高斯轨道提供更好的结果（在更坏的情况下给出等效质量的结果）。没有遇到伪造的影响。 （C）1997 John Wiley＆Sons，Inc. [参考：12]
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