电负性

The theoretical system for describing the structures of organic and drug molecules using 3 types of molecular electronegativity-distance is created based on various atomic types and atomic attributes. These MEDVs include MEDV-4 based on 4 atomic types and relative electronegativity and relative bond length to carbon atom, and molecular holographic distance vector based on 13 atomic types and relative bond length to carbon atom, and MEDV-13 based on 13 atomic types and atomic attributes and the modified electrotopological state index.

通过不同原子类型与原子属性划分方案，创建了3种形式的分子电性距离矢量即以4种原子类型划分方案和以碳原子为标准的相对电负性与相对键长为基础的分子电性距离矢量MEDV-4、以13种原子类型划分方案和相对键长为基础的全息分子距离矢量MHDV、以13种原子类型与43种原子属性划分方案以及修饰的电拓扑状态指数和拓扑距离为基础的分子电性距离矢量MEDV-13等3种矢量描述子表征分子结构的理论体系。

Unfortunately, it has been shownthat these methods are not suitable to study about chemical bonds due to not involvingchemical bonds. In order to consider chemical bonds obviously, we have proposed an atom-bondelectronegativity equalization model on the basis of density-functionaltheory and electronegativity equalization principle. The main contents of our atom-bond electronegativity equalization model contain:(1)Considering the fact that there are varies of chemical bonds in molecules andpartitioning the molecular electron density as summations of atomic electron densitiesand chemical bond's electron densities, we obtained the basic equations of atom-bondelectronegativity equalization model: the expression of the total energy 〓, theexpression of the atom electronegativity 〓 and the expression of the bondelectronegativity 〓.

为了明确地考虑和处理分子中存在的化学键，以便能够更好地描述体系中的电荷分布进而准确地描述分子体系中的有关物理化学性质，尤其是与化学键有关的物理化学性质，我们在密度泛函理论和电负性均衡原理基础上提出了原子-键电负性均衡模型，原子-键电负性均衡模型的主要内容是：(1)考虑到分子体系中存在各种化学键这个事实，将分子空间看成是由原子区和化学键区组成的，将分子的单电子密度表达成为分子中各组成原子的单电子密度和各化学键的单电子密度的加和，从而得到了原子-键电负性均衡模型的基本方程：分子体系总能量〓和分子中原子电负性〓和化学键电负性〓表达式。

Since most of the large molecules containing phosphorus element have double bonds, it is necessary to consider the special structures of double bonds in order to deal with these large systems more accurately. So, based on density functional theory and electronegativity equalization principle, applying a general atom-bond electronegativity equalization method , using separated program, through regression and least-squares optimization , the parameters of atoms and bonds in molecules are determined . By these parameters , the charge distributions and the energy of some molecules containing phosphorus element, especial the fragment of DNA, RNA, are calculated . The results are quite good.

由于这些含磷生物大分子体系都含有双键，为了明确的处理双键，进而更准确的解释带有双键和共轭双键的含磷生物大分子结构与性质的关系，我们以密度泛函理论~([1-4])和电负性均衡原理~([5-9])为基础，应用和开发原子-键电负性均衡方法中的σπ模型，利用最小二乘法，拟合确定了一些分子（含碳、氮、氧、氢以及磷等原子）的各种类型原子及化学键区域的参数，并利用上述参数计算了一些多聚核苷酸的电荷分布以及分子的总能量，进行了讨论，得到的结果可以和从头算相媲美。

Electronegativity is defined as the ability of an atom in a molecule to attract electrons to itself.

电负性是元素的原子在分子中吸引电子的能力。1932年Pauling首先提出了电负性的概念。

We have built and developed an atom-bond electronegativity equalization model on the basis of density functional theory and electronegativity equalization principle.

我们以密度泛函理论和电负性均衡原理为基础，建立和发展了原子-键电负性均衡模型。

In the framework of density functional theory, the development of electronegativity, electronegativity equalization theory and their applications for exploring some molecular properties are overviewed.

文摘：以密度泛函理论为框架，综述电负性和电负性均衡理论的发展及其在探讨各种分子性质时的应用。

We have built and developed an atom-bond electron-egativity equalization σπ model on the basis of density functional theory and electronegativity equalization principle.

我们以密度泛函理论和电负性均衡原理为基础，建立和发展了原子-键电负性均衡方法中的σπ模型。

A formula for non-dimensional synthetic electronegativity was obtained by multiple regression analysis. The correlation coefficient (R=0.9844) and test of significance Sig.

采用回归分析法，对周期表中除零族、氢及放射性元素之外的77种元素的Pauling电负性X(下标 P进行回归分析，得到了一个无量纲的综合性的电负性计算公式，相关系数(R=0.9844)和回归方程F检验的显著性水平Sig。

With the adoption of basic principles of quantum chemistry and Sonderson's theory of the relationship between elements' electronegativity and their valences, assumptions and models are made to deduce some simple calculations.

根据Sonderson提出的元素的电负性与它们的价态的关系，按照量子化学的基本原理和提出的假设和模型，推得电负性和双原子分子健能的简单计算公式。

Based on density functional theory and electronegativity equalization principle,applying an atom-bond electronegativity equalization σπ model,using a separated program,we calculated the charge distributions and dipole moments of guanine tautomers.

以密度泛函和电负性均衡原理为基础发展的原子-键电负性均衡方法的σπ模型。并结合自编程序，计算了鸟嘌呤五种异构体的电荷分布和偶极矩，计算结果表明，所计算出的电荷分布可以和从头算结果很好地关联。所计算的偶极矩与其它从头计算方法和力场方法相比总体趋势相同，进一步说明了ABEEMσπ模型的合理性

The labia have now been sutured together almost completely.The drains and the Foley catheter come out at the top.

此刻阴唇已经几乎完全的缝在一起了，排除多余淤血体液的管子和Foley导管从顶端冒出来。

To get the business done, I suggest we split the difference in price.

为了做成这笔生意，我建议我们在价格上大家各让一半。