检索结果-南通市图书馆

The Laplacian spread.of Bicyclic Graphs

Journal of Mathematical Research and Exposition 2010年第1期30卷 17-28页

作者： Yi Zheng FAN Shuang Dong LI Ying Ying TAN School of Mathematical Sciences Anhui University Anhui 230039 P. R. China Department of Mathematics & Physics Anhui University of Architecture Anhui 230022 P. R. China

The Laplacian spread.of a graph is defined to be the difference between the largest eigenvalue and the second smallest eigenvalue of the Laplacian matrix of the graph. In our recent work, we have determined the graphs with maximal Laplacian spread. among all trees of fixed order and among all unicyclic graphs of fixed order, respectively. In this paper, we continue the work on Laplacian spread.of graphs, and prove that there exist exactly two bicyclic graphs with maximal Laplacian spread.among all bicyclic graphs of fixed order, which are obtained from a star by adding two incident edges and by adding two nonincident edges between the pendant vertices of the star, respectively.

关键词： bicyclic graph Laplacian matrix spread.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study on the construction of satisfactory nonorthogonal localized molecular orbitals

引用

Science China Chemistry 2004年第1期47卷 1-9页

作者： FENG Huasheng BIAN Jiang LI Lemin State Key Laboratory of Rare Earth Materials and Applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China State Key Laboratory of Rare Earth Materials and Applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China State Key Laboratory of Rare Earth Materials and Applications College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

Comparing to orthogonal localized molecular orbitals (OLMO), the nonorthogonal localized molecular orbitals (NOLMO) exhibit bonding pictures more accordant with those in the traditional chemistry. They are more contracted, so that they have a better transferability and better performances for the calculation of election correlation energies and for the linear scaling algorithms of large systems. The satisfactory NOLMOs should be as contracted as possible while their shapes and spatial distribution keep in accordance with the traditional chemical bonding picture. It is found that the spread.of NOLMOs is a monotonic decreasing function of their orthogonality, and it may reduce to any extent as the orthogonality descends. However, when the orthogonality descends to some point, the shapes and spatial distribution of the NOLMOs deviate drastically from the traditional chemical bonding picture, and finally the NOLMOs tend to linear dependence. Without the requirement of orthogonalization, some other constraints have to be imposed for constructing satisfactory NOLMOs by minimizing their spread.functional. It is shown that satisfactory results can be generated by coupling the minimization of orbital spread.functionals with the maximization of the distances between orbital centroids.

关键词： quantum chemical calculation, chemical bonding, nonorthogonal localized molecular orbital, orbital spread.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：