Validity of the Geometric Model of Ovaloid Polymers Based on Simpler Molecules

The shape parameter obtained from the geometric model of Ishihara and Hayashida for ovaloid polymers, together with the scaled-particle theory, are applied to a mixture of methane and ethylene. The results are in good agreement with the experimental values, indicating the validity of the model and suggesting application to other polymer properties.     

用升降算符法计算多原子分子振动-转动能级

自70年代起,Handy^[1]等,用变分法计算了H₂、SO₂等分子的振动-转动光谱,所得结果与实验吻合。但因在于计算久期行列式元素的积分,其计算方法不易推广。     

A Simple Method for Estimating the Solubility Parameter of Small Molecules and Polymeric Materials

Russian Journal of Applied Chemistry - The study relates to the problem of selecting a solvent for organic polymers during their chemical processing. Based on the method of Askadsky, simple schemes...     

Calculation of Heats of Vaporization of Long Chain Molecules by Group Contribution Method

Abstract

Benson's additivity rule has been used to compute the heat of vaporization (ΔH ^o _v) of long chain molecules includes n-alkylcyclopentanes, and n-alkylcyclohexanes and n-alkylbenzenes. From the error analysis empirical equations have been obtained which accurately predicts the ΔH ^o _v of these substituted n-alkanes. For simple n-alkanes it is observed that no modification is necessary in Benson's method. The present simple and elegant empirical approach can be utilized to calculate other thermodynamic properties of long chain molecules where such data are generally scarce.     

有机化合物分子不饱和度的计算

在推导有机未知物结构的时候,由分子式计算出不饱和度可以提供有用的信息。贵刊曾载文讨论不饱和度的计算[1]。     

The Generalized Parameterization Procedure for Semiempirical MO Method and Calculation of ionization Potentials for the Fourth-Period Element Molecules

This study presents a set of the generalized parameters from a unique resource for the elements which are from the first-period to the fourth-period (H to Xe). In addition, these series of parameters are used to examine forty-five compounds consisting of the fourth-period elements and the second-period transition metal elements. Herein, the major calculation theory applied is the s-p-d INDO MO method. To verify the reliability of the molecular calculations, similar calculations of the STO-3G and STO-3G* ab inito methods, along with the semiempirical PM3 and AM1 methods are also compared. Results in this study demonstrate that the s-p-d INDO MO computed with the generalized parameter is the best available method.     

表征O－H解离能参数的AM1计算

对17种酚类化合物用半经验量子化学方法AM1计算了表征O－H解离能的参数△HOF值,即酚类化合物与其经抽氢反应产生的自由基生成热之差。经过与实验测定的17种酚类化合物的O－H解离能比较,评价了AM1方法在计算△HOF值方面的有效性。发现AM1计算的△HOF值与O－H解离能有很好的相关性(γ=0.9495),优于经验方法,比如加和规则对O－H解离能的预测。虽然AM1方法在计算间位取代对O－H解离能的贡献方面是无效的,但将用于计算解离能类的参数以预测抗氧化剂活性还是可行的。     

The Calculation for the Molecular Position Electronegativity of Organic Molecules

The molecular position electronegativity (MPEN) is a new concept and based on the auther's studying of group electronegativity^[1,2]. MPEN represents the power of attracting an electron of the center atom situated different molecular environment. MPEN is defined as the electronegativity of the center atom situated different molecular environment and this is affectde by neighbors of the center atom.     

三原子分子振动光谱的相互作用模式计算

Using the quantum self-trapping theory, the interaction model (IM) for calculation of vebrational spectroscopy for tri-atomic molecules has been devoloped, and the results for 16O3, 18 O3, SO2, HCN and DCN are in good agreement with the experirnental data. It shows that this method is superior to the NM and LM methods, and it is applicable to the calculation of high-excited vibrational states especially.     

Association and Shape of Molecules Using Free Length Theory

Abstract

Traditionally workers engaged in calculation of the ultrasonic velocity in liquid mixtures using Jacobson's Free Length Theory (FLT) arrive at the conclusion that the predictions of FLT produce large deviations when compared with experimental velocities. Such workers seemed to have ignored the necessity of incorporating two parameters in FLT as originally suggested by Jacobson himself: one, to account for the association, and the other, for the shape of the component molecules in the mixture. By introducing the association factor and deriving explicit expressions for different shapes of the molecules, the present work has demonstrated that FLT might be made to predict ultrasonic velocities in the mixtures better. Also this approach can very well be used to account for molecular associations and shapes.     

Investigation of a Simple Pickup Method for Doping Molecules into Water Clusters

A capillary pickup method was investigated for doping molecules into water clusters, which were produced by supersonic expansion, and underwent a sticking collision with a crossed beam from the capillary. This method was applied to H₂O clusters in a beam with pickup of DCl, CH₃OH, NH₃, CO₂ and D₂O molecules, however, we found only molecule of DCl can be picked up by water clusters with the capillary configuration in those tested dopants. Meanwhile, two different distances between the capillary to the nozzle were investigated based on the collected mass spectra, and we found that the smaller distance can obtain the stronger mixed cluster intensity.     

Calculation of the Segmental Order Parameter for a Polymer Chain in Good Solvent

We have calculated the segmental tensor order parameter (second moment of orientation distribution function) of flexible polymer chains in a weak good solvent with fixed end‐to‐end distance and fixed segment length. Using the Edwards model for polymer chains with excluded volume interaction, we have performed direct perturbation expansions to obtain the two‐vector correlation function in one loop order. Our results indicate that distribution of tensor order parameter is not homogeneous along the chain as expected for ideal Gaussian statistics. Segmental order is lower as compared to Gaussian chains and decays toward the chain ends. These results are in agreement with computer simulation studies.

     

胰岛素分子主链构象的CNDO／2计算和比较

对蛋白质分子进行量子化学计算常采用如下方法:以肽基和残基侧链为基本计算单元,使对蛋白质分子的计算分解成各次单元的计算(图10)。计算时往往根据构象图选择代表点以减少工作量。例如,计算木瓜蛋白酶时,根据其构象图,212个肽基被分为10组,每组中选取1个代表点进行计算。用同样的方法处理残基侧链的计算。但该方法     

胰岛素分子相互作用能的计算

胰岛素分子间的相互作用是人们所关心的一个课题,它对探讨胰岛素及其类似物与受休的相互作用和它们在溶液中的行为有着重要的意义,本文在前文工作的基础上,计算了两个胰岛素分子在不同距离和不同取向时的相互作用能,并试图对上述问题的研究提供线索。 我们从胰岛素两聚体的晶体结构数据出发,找出两个单体分子相距最近的三对点,求其中点坐标,在过该三点的平面上作一条垂线,作为分子间平移和转动的参考轴,固     

Acceleration of Correlation-corrected Vibrational Self-consistent Field Calculation Times for Large Polyatomic Molecules

Acceleration of the correlation-corrected Vibrational self-consistent field (CC-VSCF) method for anharmonic calculations of vibrational states of polyatomic molecules is described. The acceleration assumes pairwise additive interactions between different normal modes, and employs orthogonality of the single-mode vibrational wavefunctions. This greatly reduces the effort in computing correlation effects between different vibrational modes, which is treated by second order perturbation theory in CC-VSCF. The acceleration can improve the scaling of the overall computational effort from N ⁶ to N ⁴, where N is the number of vibrational modes. Sample calculation times, using semi-empirical potential surfaces (PM3), are given for a series of glycine peptides. Large computational acceleration, and significant reduction of the scaling of the effort with system size, is found and discussed.     

有机共轭分子电子结构的计算

根据分子结构的共振理论,为PPP方法选择了一套合理的经验参数。应用CNDO/2方法和PPP方法计算了有机共轭分子的电子能级、最低三重态激发能及增感染料分子的半波电位。     

Calculation of Self-Attenuation Factors in Gamma-Ray Spectrometry for Samples of Arbitrary Shape

The distribution of photons detected in a spectrometer as a function of their path length in the sample can be approximated by a one-parametric family of functions. The members of the family, having different average path lengths, describe the transport of photons in samples of different shapes. The value of the parameter corresponding to the actual counting geometry is obtained from the measured average path of photons in the sample. The self-attenuation factor as a function of the attenuation coefficient is calculated as the Laplace transform of the member of the family, defined by the extracted value of the parameter.     

共轭分子总能量的计算

由本征多项式直接求共轭分子π电子总能量已有很多报导。本工作在已知本征多项式基础上,根据多项式根与系数关系,导出计算π电子总能量关系式。这方面工作尚未见报导。我们用图论计数的办法给出简便计算共轭分子本征多项式的方法。