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21.
Yibo Lei Bingbing Suo Yusheng Dou Yubin Wang Zhenyi Wen 《Journal of computational chemistry》2010,31(8):1752-1758
Multireference configuration interaction with single and double excitations (MRCISD) as well as its analytic CI gradients has been implemented in the semiempirical framework. The hole‐particle symmetry and a mixed driven model for computing coupling coefficients have been used in the new code that allows us to perform MRCI and gradient calculations with higher efficiency and less storage requirements. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
22.
We present a theoretical study of dissociative photoionization of H2 via the 1Πu symmetry in the photon energy range 30–43 eV. Our results explain the various peaks observed in the experiments below 40 eV and illustrate, in particular, the important role of the 2Πu(2pπu) ionization threshold. At higher photon energies, they suggest the existence of new resonance structures that may be associated with doubly excited states of H2 lying above the third and fourth ionization thresholds (the Q3 and Q4 resonance series). From the calculated resonance parameters, we conclude that the dominant mechanism at high photon energies should involve the Q4 (and probably higher) doubly excited states of H2. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2002 相似文献
23.
Pancracio Palting 《International journal of quantum chemistry》1998,67(6):343-357
The step operators of the two-dimensional isotropic harmonic oscillator are shown to be separable into the basis elements of two disjoint Heisenberg Lie algebras. This separability leads to two sets of irreducible tensors, each of which is based upon its associated underlying Heisenberg Lie algebra. The matrix elements of these tensors are evaluated, along with those of some vibrational operators of physical interest. The possibility of other irreducible tensors are discussed and their usefulness is compared with that of those found here. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 67: 343–357, 1998 相似文献
24.
Reduced dimensionality (3,2)D NMR experiments and their automated analysis: implications to high‐throughput structural studies on proteins 下载免费PDF全文
Ramakrishna V. Hosur 《Magnetic resonance in chemistry : MRC》2015,53(2):79-87
Protein NMR spectroscopy has expanded dramatically over the last decade into a powerful tool for the study of their structure, dynamics, and interactions. The primary requirement for all such investigations is sequence‐specific resonance assignment. The demand now is to obtain this information as rapidly as possible and in all types of protein systems, stable/unstable, soluble/insoluble, small/big, structured/unstructured, and so on. In this context, we introduce here two reduced dimensionality experiments – (3,2)D‐hNCO canH and (3,2)D‐hN coCA nH – which enhance the previously described 2D NMR‐based assignment methods quite significantly. Both the experiments can be recorded in just about 2–3 h each and hence would be of immense value for high‐throughput structural proteomics and drug discovery research. The applicability of the method has been demonstrated using alpha‐helical bovine apo calbindin‐D9k P43M mutant (75 aa) protein. Automated assignment of this data using AUTOBA has been presented, which enhances the utility of these experiments. The backbone resonance assignments so derived are utilized to estimate secondary structures and the backbone fold using Web‐based algorithms. Taken together, we believe that the method and the protocol proposed here can be used for routine high‐throughput structural studies of proteins. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
25.
Tuvi Etzion 《组合设计杂志》2008,16(2):137-151
A doubly constant weight code is a binary code of length n1 + n2, with constant weight w1 + w2, such that the weight of a codeword in the first n1 coordinates is w1. Such codes have applications in obtaining bounds on the sizes of constant weight codes with given minimum distance. Lower and upper bounds on the sizes of such codes are derived. In particular, we show tight connections between optimal codes and some known designs such as Howell designs, Kirkman squares, orthogonal arrays, Steiner systems, and large sets of Steiner systems. These optimal codes are natural generalization of Steiner systems and they are also called doubly Steiner systems. © 2007 Wiley Periodicals, Inc. J Combin Designs 16: 137–151, 2008 相似文献
26.
主要研究随机矩阵逆特征值问题.特别是对称双随机矩阵和列随机矩阵逆特征值问题.对参考文献[1]与[2]的结论作了一些推广.并给出了—个数值例子. 相似文献
27.
Consider the problem of scattering of electromagnetic waves by a doubly periodic Lipschitz structure. The medium above the structure is assumed to be homogenous and lossless with a positive dielectric coefficient. Below the structure there is a perfect conductor with a partially coated dielectric boundary. We first establish the well‐posedness of the direct problem in a proper function space and then obtain a uniqueness result for the inverse problem by extending Isakov's method. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
28.
This note proves a conjecture of Merris that the minimal value of entries of the doubly stochastic matrix of the degree antiregular graph En of order n ≥ 3 is equal to (l/2(n + l)). 相似文献
29.
G.S. Wang 《Theoretical and Applied Fracture Mechanics》2004,42(3):668
In this paper, an extremely accurate and efficient method for computing the interaction of a set of or multiple sets of general doubly periodic cracks has been presented on the basis of superposition principle, pseudo-traction method, and isolating analysis technique. A great number of typical examples are given in this paper. The stress intensity factors (SIF), the minimum strain energy density factors (SED) of crack tip and the critical stress (CRS) of crack growth are calculated with the accuracy of six significant digits for the rectangularly distributed periodic cracks and five significant digits for the general doubly periodic cracks. The relation of the interaction effect of the double periodic cracks with the periods and the ratio of crack length to crack spacing is analyzed. Also in this paper, the key technique problems for this method are discussed. 相似文献
30.
该文研究了一类正倒向重随机微分方程, 在某些自然的单调性假设下, 得到了解的存在唯一性结果. 相似文献