期刊：
Computational and Theoretical Chemistry,1991年226(3-4):197-209 ISSN：2210-271X
作者机构：
Department of Chemistry, Central China Normal University, Wuhan, 430070 People's Republic of China
摘要：
This is an elementary study on the extremum method in quantum chemistry. The definitions of the differentiation of a real matrix function F(t) with respect to the variable t and a scalar function F(X) =φ, which is the trace of a product of several matrices, with respect to a variable matrix X have been introduced. The mathematics is not novel but the suggested procedure employed to the extremum problems appearing in quantum chemistry may be different from the ordinary treatments. Some elementary applications will be reported in the second part. First of all, we shall show a general rule for finding the resultant expression for the derivative ∂φ/∂X in this paper. In quantum chemistry, we usually have to find the extremum value of gYj¦Q¦Ψj = CjTQCj subject to the restrictive condition that CjTMxCj = 1 for an arbitrary state Ψj first, and extend the result to a set of states. A matrix eigenvalue equation can then be obtained, but here, a whole set of {Ψj} will be dealt with at one time. The matrix eigenvalue equation Q(CW) = Mx (CW) Λx can be obtained from the given rule very directly and very simply. Only one basis set is used in this situation. The other main problems discussed in this paper are the necessary and sufficient conditions for finding an extremum of tr L = tr (BTPC) subject to the restrictive conditions of orthonormalities. There are two basis sets considered in this situation. An important conclusion we have found is that the matrix BTPC must be symmetric.
期刊：
Computational and Theoretical Chemistry,1991年231:39-46 ISSN：2210-271X
通讯作者：
ZHAN, CG
作者机构：
Department of Chemistry, Central China Normal University, Wuhan 430070 People's Republic of China
通讯机构：
[ZHAN, CG] C;CENT CHINA NORMAL UNIV, DEPT CHEM, WUHAN 430070, PEOPLES R CHINA.
摘要：
It is shown that the procedures for constructing the symmetry orbitals proposed in preceding papers can be extended and simplified, and may be employed to construct the symmetry orbitals in very large molecular systems by partitioning the atomic orbitals into many sets.
作者机构：
CENT CHINA NORMAL UNIV,INST ORGAN SYNTH,WUHAN,PEOPLES R CHINA.;CHINESE ACAD SCI,INST BOT,PHOTOSYNTH LAB,BEIJING,PEOPLES R CHINA.;[LIU, BL] LEIDEN UNIV,DEPT BIOPHYS,HUYGENS LAB,POB 9504,2312 AV LEIDEN,NETHERLANDS.
通讯机构：
[LIU, BL] L;LEIDEN UNIV,DEPT BIOPHYS,HUYGENS LAB,POB 9504,2312 AV LEIDEN,NETHERLANDS.
期刊：
Computational and Theoretical Chemistry,1991年236(3-4):321-331 ISSN：2210-271X
通讯作者：
ZHAN, CG
作者机构：
Department of Chemistry, Central China Normal University, Wuhan 430070 The People's Republic of China
通讯机构：
[ZHAN, CG] C;CENT CHINA NORMAL UNIV, DEPT CHEM, WUHAN 430070, PEOPLES R CHINA.
摘要：
The application of the maximum overlap symmetry orbital (MOSO) method to conjugated systems is discussed briefly. The MOSO method can be employed to construct not only the symmetry orbitals and the molecular orbitals in alternant conjugated systems, but also the symmetry orbitals in non-alternant systems. It is shown that under the Huckel approximation the matrix MM+ can be written out directly from the molecular skeleton and may be treated by using chemical graph theory. Because the matrix MM+ of a system can be regarded as the Huckel matrix of a smaller system, the maximum overlap symmetry molecular orbital (MOSMO) calculation results can be easily obtained from those of the smaller systems. For homonuclear conjugated systems and for systems in which two kinds of atom appear alternantly, the MOSMOs and the corresponding molecular orbital (MO) energies obtained by the MOSMO calculation are the same as the MOs and the MO energies calculated by the Huckel molecular orbital method.
期刊：
Journal of Inorganic Biochemistry,1991年43(2-3):210 ISSN：0162-0134
作者机构：
[J.E. Shi; P.L. Chen; W.Q. Liu; Y.Q. Jiang] Department of Chemistry, Huazhong Normal University, Wuhan, 430070, P. R. China;[C.L. Liu] Department of Chemistry, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China
摘要：
The radical alkylation of 1,4-naphthoquinone with various lengths of fatty acids [H(CH2)nCO2H] in the presence of (NH4)2S2O8 and AgNO3 was studied. A simple and effective method was found for the synthesis of vitamin-K derivatives with different lengths of alkyl side chain. Two types of vitamin-K derivatives were synthesized. The first type, 2-alkyl-1,4-naphthoquinones, was synthesized by a single step of radical alkylation of 1,4-naphthoquinone with different lengths of fatty acids. The second type, 2-alkyl-3-methyl-1,4-naphthoquinones, was synthesized by radical alkylation of 2-methyl-1,4-naphthoquinone using the same reaction as for the first type, or by radical methylation of the first type. Our results show that the former method is suitable for the synthesis of long-side-chain (n > 11; n, number of carbon atoms in chain of the fatty acid) vitamin-K derivatives, whereas the latter method is better for the synthesis of short-side-chain (n < 11) vitamin-K derivatives. The structures of these newly synthesized vitamin-K derivatives were identified by UV, IR, H-1 NMR and MS spectra.
期刊：
Computational and Theoretical Chemistry,1991年226(3-4):339-349 ISSN：2210-271X
通讯作者：
ZHAN, CG
作者机构：
Department of Chemistry, Central China Normal University, Wuhan, 430070 People's Republic of China
通讯机构：
[ZHAN, CG] C;CENT CHINA NORMAL UNIV, DEPT CHEM, WUHAN 430070, PEOPLES R CHINA.
摘要：
On the basis of a general conclusion expressed in the Appendix, in this paper, we firstly discuss the symmetry properties of the orthogonalized AO basis set obtained by use of the canonical orthogonalization, then suggest a simple and systematic method for constructing a set of ortho-normalized symmetry orbitais which are fully classified according to the basis vectors for the rows of the irreducible representations of the corresponding molecular point symmetry group. By use of the orbitais obtained, the Hamiltonian or Fock matrix can be fully block diagonalized according to the rows of the irreducible representations.
期刊：
Computational and Theoretical Chemistry,1991年231:47-56 ISSN：2210-271X
通讯作者：
ZHAN, CG
作者机构：
Department of Chemistry, Central China Normal University, Wuhan 430070 People's Rep. of China
通讯机构：
[ZHAN, CG] C;CENT CHINA NORMAL UNIV, DEPT CHEM, WUHAN 430070, PEOPLES R CHINA.
摘要：
A maximum overlap population principle is introduced to give a very simple approximate scheme for calculating bond order, atomic valence and atomic charge directly from the eigenvectors of the AO overlap matrix without performing the ordinary molecular orbital calculation. The calculated results are close to or on the whole coincident with those obtained from the canonical molecular orbitals constructed by use of the ab initio calculation, which shows that the calculation scheme suggested in this paper is feasible.
期刊：
Computational and Theoretical Chemistry,1991年231:33-38 ISSN：2210-271X
通讯作者：
ZHAN, CG
作者机构：
Department of Chemistry, Central China Normal University, Wuhan 430070 People's Republic of China
通讯机构：
[ZHAN, CG] C;CENT CHINA NORMAL UNIV, DEPT CHEM, WUHAN 430070, PEOPLES R CHINA.
摘要：
Based on the extended maximum-overlap criterion proposed previously, a set of generalized equations were obtained for constructing the orthogonalized maximum overlap symmetry orbitals of an arbitrary molecule. Particularly for molecules which do not involve rings with an odd number of atoms, the orthogonalized maximum overlap symmetry orbitals obtained can be used not only to block diagonalize the Fock matrix, but also as the initial molecular orbitals in the self-consistent-field calculation.
作者机构：
Department of Chemistry, Central China Normal University, Wuhan, People's Republic of China
通讯机构：
[LIU, F] C;CENT CHINA NORMAL UNIV,DEPT CHEM,WUHAN,PEOPLES R CHINA.
摘要：
This paper describes a generalized and extended treatment of the preceding papers in which the maximum overlap method was employed but the results were limited by the. condition that the number of Iigands surrounding the central atom should be two, that is, k = 2 in molecule MLko Based on the special assumption. that the angles < LpMLq = a between any two M-Lj bonds in molecule MLk are equal, many general formula s related to the diagonal matrix D (Jo), unitary matrix U", overlap matrix Sl and the bond strength F are derived. The properties of matrix SST are also discussed.
