Population analyses of valence-bond wavefunctions and BeH2

A method for calculating occupation numbers and making a population analysis is proposed. The method is designed particularly for use with wavefunctions written in terms of non-orthogonal bases. An application to the valence-bond wavefunction of BeH₂ is given and the results are compared with other population analysis schemes which have been proposed.     

Stability of a microwave heated fluid Layer

When a time harmonic electromagnetic wave impinges on a slaba certain portion of the wave creates heat within the slab throughdipolar and ohmic heating. The electrical and thermal propertiesof the material dictate the dynamical nature of the heatingprocess, as well as the steady-state temperature profile. Thematerial considered here is a slab of fluid. We consider thecase where the fluid is bounded by thin rigid layers of transparentmaterial. The steady-state heating profile governs the typesof convective motions that can occur and also affects the stabilitycharacteristics of temperature, pressure and velocity perturbationsintroduced in the slab. The main objective here is to examinesuch stability characteristics, initially in the linear regime.Both rigid-rigid and rigid-free configurations are considered.     

Factorization of the secular determinant by constants of the motion

A discussion of the factorization by constants of the motion of the secular equation is given and formulas are obtained which relate these factors to the traces of certain operators. These traces are independent of the specific basis in the vector space, and, hence, so are the factors of the secular equation. The results are also applied to the case of factoring by a finite symmetry group.     

Radical cyclization of sugar-derived beta-(alkynyloxy)acrylates: synthesis of novel fused ethers

[formula: see text] Tributyltin radical mediated cyclization of carbohydrate-derived beta-(alkynyloxy)acrylates leading to highly functionalized cis- and trans-fused bicyclic ethers of various ring sizes is described. The efficacy of the radical cyclization is nicely illustrated in the iterative construction of a trans-fused tricyclic tetrahydropyran.     

Application of the Kohn-Sham formalism to quantum dots with realistic dimensions and constrictions

We demonstrate that the Kohn-Sham self-consistent scheme used successfully for studying the electronic properties of periodic systems can be scaled to calculate the properties of quantum dots without and with constrictions at length and energy scales comparable to those currently attainable experimentally. This method can be a useful tool for studying low-dimensional systems in the extreme quantum limit.     

Iterative calculation of eigenvalues and eigenvectors of large,real matrix systems with overlap

An improved method for obtaining a few eigenvalues and eigenvectors of the symmetric matrix system is presented: where S ≠ I . The method allows us to handle larger systems more easily than any other known to the author. It requires the inversion of S , and N³ step, but thereafter each eigenvector and eigenvalue is obtained in a length of time proportional to N². The relation of this method to the MOR and MMOR methods developed recently for handling the case, S = I , is discussed.     

ICP-AES法测定内蒙古地区六种沙生木本植物中金属元素

采用ICP-AES法分别对内蒙古地区梭梭、小叶锦鸡儿、沙冬青、红柳、沙枣和沙柳等六种沙生木本植物中金属元素进行了测定和分析。该方法的加标回收率为94.98％～120.25％,RSD＜3.4％,具有良好的准确度和精密度。结果表明,常量元素Ca,K,Mg,Na,Al及植物生命活动所必需的微量元素Fe,Mn,Cu,Zn在六种沙生木本植物中表现为不同的含量顺序,且Fe,Mn,Cu,Zn四种元素的含量均低于陆生高等植物的平均含量。该测定结果为改善西部地区生态环境,选择优良防风固沙树种提供可靠的数据和理论依据。