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991.
A. Canal Neto F. E. Jorge M. De Castro 《International journal of quantum chemistry》2002,88(2):252-262
We have generated Gaussian basis sets (GBSs) for the neutral and the first 20 cations members of the isoelectronic series of each ground state atom from He to Ne with the improved generator coordinate Hartree–Fock (IGCHF) method. For all atomic species studied here, our total energy errors are smaller than those calculated by the original GCHF method using GBSs of the same sizes. The largest difference between our total energy results and those computed with a numerical Hartree–Fock approach is equal to 215 μhartree for Co17+. We also compare the ionization potentials obtained with the IGCHF with the corresponding experimental values. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 252–262, 2002 相似文献
992.
The Coupled Perturbed Hartree-Fock (CPHF) scheme has been implemented in the CRYSTAL06 program, that uses a gaussian type basis set, for systems periodic in 1D (polymers), 2D (slabs), 3D (crystals) and, as a limiting case, 0D (molecules), which enables comparison with molecular codes. CPHF is applied to the calculation of the polarizability alpha of LiF in different aggregation states: finite and infinite chains, slabs, and cubic crystal. Correctness of the computational scheme for the various dimensionalities and its numerical efficiency are confirmed by the correct trend of alpha: alpha for a finite linear chain containing N LiF units with large N tends to the value for the infinite chain, N parallel chains give the slab value when N is sufficiently large, and N superimposed slabs tend to the bulk value. CPHF results compare well with those obtained with a saw-tooth potential approach, previously implemented in CRYSTAL. High numerical accuracy can easily be achieved at relatively low cost, with the same kind of dependence on the computational parameters as for the SCF cycle. Overall, the cost of one component of the dielectric tensor is roughly the same as for the SCF cycle, and it is dominated by the calculation of two-electron four-center integrals. 相似文献
993.
Systematic calculations of the structures of the H2CO, F2CO, Cl2CO, HClCO, HFCO, and FClCO molecules in the S0 and T1 states were performed using the B3LYP and MP2 methods with different AO basis sets and also at the CCSD(T)/cc-pV(T+d)Z level
of theory. The saturation of the correlation consistent sequence of basis sets cc-pV(N+d)Z (N = D, T, Q, and 5) and aug-cc-pV(N+d)Z
(N = D, T, and Q) was studied. Recommendations for choosing the calculation method are given. The relativistic corrections
were estimated. The influence of the number and type of halogen atoms on the geometric parameters of the molecules in the
S0 and T1 states and the heights of inversion barriers in the T1 state was investigated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2625–2635, December, 2005. 相似文献
994.
Karin Eichkorn Florian Weigend Oliver Treutler Reinhart Ahlrichs 《Theoretical chemistry accounts》1997,97(1-4):119-124
We present auxilliary basis sets for the atoms H to At – excluding the Lanthanides – optimized for an efficient treatment
of molecular electronic Coulomb interactions. For atoms beyond Kr our approach is based on effective core potentials to describe
core electrons. The approximate representation of the electron density in terms of the auxilliary basis has virtually no effect
on computed structures and affects the energy by less than 10−4 a.u. per atom. Efficiency is demonstrated in applications for molecules with up to 300 atoms and 2500 basis functions.
Received: 17 December 1996 / Accepted: 8 May 1997 相似文献
995.
HUANG Wei YUAN Cai Ansaldi Mireille Morelli Xavier Edward J. Meehan CHEN Li-Qing HUANG Ming-Dong 《结构化学》2007,26(5):594-598
TorI, a Tor system inhibitor acting through protein-protein interaction with the TorR response regulator, is an excisionase that interacts with the integrase and DNA during prophage excision. It has been crystallized by the vapor-diffusion method using polyethylene glycol 3350 as a precipitant at pH 8.5. The X-ray diffraction data sets from the TorI crystal was collected at a resolution of 2.1 , using a synchrotron source. The crystal belongs to primitive monoclinic lattice with cell parameters of 46.210 × 53.992 × 73.561 相似文献
996.
Zuzana Benkova Andrzej J. Sadlej Roma E. Oakes Steven E. J. Bell 《Theoretical chemistry accounts》2005,113(4):238-247
Reduced–size polarized (ZmPolX) basis sets are developed for the second–row atoms X = Si, P, S, and Cl. The generation of these basis sets follows from a simple physical model of the polarization effect of the external electric field which leads to highly compact polarization functions to be added to the chosen initial basis set. The performance of the ZmPolX sets has been investigated in calculations of molecular dipole moments and polarizabilities. Only a small deterioration of the quality of the calculated molecular electric properties has been found. Simultaneously the size of the present reduced–size ZmPolX basis sets is about one-third smaller than that of the usual polarized (PolX) sets. This reduction considerably widens the range of applications of the ZmPolX sets in calculations of molecular dipole moments, dipole polarizabilities, and related properties. 相似文献
997.
Krzysztof Wolinski Björn O. Roos Andrzej J. Sadlej 《Theoretical chemistry accounts》1985,68(6):431-444
The idea of the basis set polarization which follows from the known dependence of basis set functions on the perturbation strength is applied to the calculation of the dipole moment derivatives with respect to nuclear displacements. The differentiation of the dipole moment function is replaced by the straightforward evaluation of derivatives of the intramolecular electric field with respect to the external electric field strength. The method and its efficiency are illustrated by a series of calculations of the dipole moment derivatives for the water molecule. Already a polarized basis set of 26 CGTO's derived from the minimal CGTO basis set provides fairly reasonable results. 相似文献
998.
D. H. Martin 《Journal of Optimization Theory and Applications》1978,25(4):579-584
It is shown that the following classes of functionsf, each defined on some subsetD of a fixed Hausdorff topological vector spaceE, are closed under the binary operation of infimal convolution: (a) the class of functionsf:D[–, ) having connectedstrict lower level sets; (b) the class of functionsf:D having compact connected lower level sets; and (c) the class of functionsf:D having compact lower level sets and for which every local minimizer is global. In (a),E need not be Hausdorff; while in (a) and (b), the word connected may be replaced by the word path-connected. 相似文献
999.
1000.
We show quantitative versions of classical results in discrete geometry, where the size of a convex set is determined by some non-negative function. We give versions of this kind for the selection theorem of Bárány, the existence of weak epsilon-nets for convex sets and the theorem of Alon and Kleitman. These methods can be applied to functions such as the volume, surface area or number of points of a discrete set. We also give general quantitative versions of the colorful Helly theorem for continuous functions. 相似文献