ORMAS-SCF 研究硅（100）表面团簇。

ORMAS-SCF study of silicon (100) surface clusters.

机构信息

Department of Chemistry, Iowa State University, Ames, Iowa 50010, USA.

出版信息

J Phys Chem A. 2010 Aug 26;114(33):8817-23. doi: 10.1021/jp101800z.

PMID:20446752

Abstract

An occupation restricted multiple active space (ORMAS) study of clusters that represent the silicon(100) surface (up to nine surface dimers) is discussed. The accuracy of three different active orbital ORMAS partition schemes for Si(100) surface clusters are compared. In addition to ORMAS-SCF calculations, generalized valence bond-perfect pairing (GVB-PP) properties are generated for comparison purposes. The ability of ORMAS to generate a reliable multiconfigurational zeroth-order wave function is systematically tested and when possible is compared to the full complete active space self-consistent field (CASSCF) method. This provides good benchmarks for the accuracy of ORMAS compared to CASSCF. It is demonstrated that ORMAS consistently provides a high degree of accuracy with a significantly reduced computational effort relative to a CASSCF calculation. For the largest cluster, for which a full CASSCF calculation is not possible, ORMAS predicts that the Si(100) surface dimers are symmetric.

摘要

讨论了一种代表硅（100）表面（最多九个表面二聚体）的簇的受限多活动空间（ORMAS）研究。比较了三种不同的用于 Si（100）表面簇的活性轨道 ORMAS 分区方案的准确性。除了 ORMAS-SCF 计算外，还生成了广义价键-完美配对（GVB-PP）性质以进行比较。系统地测试了 ORMAS 生成可靠的多组态零阶波函数的能力，并在可能的情况下将其与完全活性空间自洽场（CASSCF）方法进行了比较。这为 ORMAS 与 CASSCF 的准确性提供了很好的基准。结果表明，与 CASSCF 相比，ORMAS 始终提供高度的准确性，同时计算工作量大大减少。对于无法进行全 CASSCF 计算的最大簇，ORMAS 预测 Si（100）表面二聚体是对称的。