Convergence process with quasi-canonical localized orbital in all-electron SCF calculation on proteins

A convergence process with a new type of localized orbital (LO) is proposed for self-consistent field (SCF) molecular orbital (MO) calculations on proteins. Recently, an all-electron density functional (DF) calculation on cytochrome c was achieved by a convergence method in which the initial electron density of a peptide was constructed by linking the electron density of small peptides. However, its convergence was slow and insufficient in SCF calculations for long peptides. In this paper a new kind of LO called the ‘quasi-canonical localized orbital (QCLO)’ is formulated and a computational process with QCLOs is proposed to improve the SCF convergence. The QCLO is localized in a certain region of a molecule, but it is also the canonical MO of the region. In test calculations on a seven-residue peptide, the error in the initial total energy calculated with QCLOs was about one twentieth of that by cut and paste of the electron density, and the number of SCF iterations was reduced markedly. Future applications of QCLO to big and complex molecules are also discussed.     

Isotope effect of hydrated clusters of hydrogen chloride,HCl(H2O) n and DCl(H2O) n (n = 0–4): application of dynamic extended molecular orbital method

The recently proposed dynamic extended molecular orbital (DEMO) method is applied to the HCl(H₂O) _n and DCl(H₂O) _n (n = 0–4) clusters in order to explore the isotope effect on their structures, wavefunctions, and energies, theoretically. Since the DEMO method determines both electronic and nuclear wavefunctions simultaneously by optimizing all parameters including basis sets and their centres variationally, we can get the different nuclear orbitals for proton and deuteron as well as their electronic wavefunctions. The positions of the centres of nuclear orbitals show that the deuteron has weaker hydrogen bonding than the proton. There are three isomers in the case of n = 3 clusters, and less stable isomers have hydrogen transferred and non-transferred structures. In the conventional MO calculation, both hydrogen transferred and non-transferred isomers are calculated to be energy minima. When we have applied the DEMO method, only the hydrogen transferred structure is obtained for HCl(H₂O)₃, while both structures are optimized for DCl(H₂O)₃. Such strong H/D dependence on the structures of the HCl(H₂O) _n and DCl(H₂O) _n clusters can be expressed directly by using the DEMO method. The present application demonstrates that the DEMO method is a useful tool for analysing the anharmonicity and vibronic effects of a hydrogen bonding system.     

FE Formulation of Detonation Important by the Stabilized Galerkin Method

We introduce a finite element formulation of Detonation problems. The detonation involves supersonic combustion waves which emanate from an exothermic chemical reaction occurring behind propagating shock waves. The development of geometrically versatile schemes is required to meet practical needs. The Galerkin/Least-squares method with entropy variables possesses good accuracy and stability properties. As a first attempt to handle chemical reaction model, we use a simple two front model which has a good performance and a flexibility in adapting to the experimental data. It is emphasized that the process of generation and propagation of the shock triple points has been demonstrated.     

草苁蓉中2个单萜苷类化合物的NMR研究

从草苁蓉75%乙醇提取物中分离得到了2个单萜苷类化合物,结合其理化性质,并通过1D NMR（¹H NMR,¹³C NMR）及¹H-¹H COSY、HSQC、HMBC、NOESY等多种波谱学方法进行结构鉴定,鉴定2个化合物分别为β-D-glucopyranose 1-(3,7-dimethyl-2-trans-6-octadienoate)(化合物1)和6,7-dihydrofoliamenthoic acid diglucoside（化合物2）,其中化合物1为新化合物,化合物2为第1次从列当科植物中获得.