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1.
In this article a matrix method for the construction of spin multiplets (spinconfigurations) is suggested in order to solve the multielectron problem for atoms and mulecules by means of configuration interaction.A simple graphical way is given to enumerate configurations and to break their set into subsets of configurations related to the given projection of the total spin of a system S
z
. It is found that all matrices in the theory of spin multiplets are convex and in cases of two, three, and four electrons are broken into blocks of an order no higher than 3.The model of the solution of the multielectron Schrödinger equation, in which the total spin of core electrons is zero, is considered. In this model the construction of linear combinations of configurations is reduced to the construction of those for but valence electrons. 相似文献
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B. N. Plakhutin E. V. Gorelik N. N. Breslavskaya M. A. Milov A.A. Fokeyev A. V. Novikov T. E. Prokhorov N. E. Polygalova S. P. Dolin L. I. Trakhtenberg 《Journal of Structural Chemistry》2005,46(2):195-203
We present a number of molecular systems for which the average values 〈?2〉 before and after annihilation of the first spin contaminant in the wave function of the unrestricted Hartree-Fock method are anomalously large (they substantially exceed the expected value S (S + 1)). An example of such systems is N@C20, for the doublet state of which the 〈?2〉 values are equal to 4.2595 before and 13.1390 after annihilation, respectively (calculated by UHF/6-31G* method). We show that four, at the least, spin multiplets (S′ = S, S + 1, S + 2, S + 3) contribute comparatively to the wave function of such systems. The relations are derived allowing one to estimate the contributions of the highest multiplets basing on the average values of 〈?2〉 before and after annihilation of the first spin contaminant. 相似文献
4.
Pharmacophore multiplets are useful tools for 3D database searching, with the queries used ordinarily being derived from ensembles
of random conformations of active ligands. It seems reasonable to expect that their usefulness can be augmented by instead
using queries derived from single ligand conformations obtained from aligned ligands. Comparisons of pharmacophore multiplet
searching using random conformations with multiplet searching using single conformations derived from GALAHAD (a genetic algorithm
with linear assignment for hypermolecular alignment of datasets) models do indeed show that, while query hypotheses based
on random conformations are quite effective, hypotheses based on aligned conformations do a better job of discriminating between
active and inactive compounds. In particular, the hypothesis created from a neuraminidase inhibitor model was more similar
to half of 18 known actives than all but 0.2% of the compounds in a structurally diverse subset of the World Drug Index. Similarly,
a model developed from five angiotensin II antagonists yielded hypotheses that placed 65 known antagonists within the top
0.1–1% of decoy databases. The differences in discriminating power ranged from 2 to 20-fold, depending on the protein target
and the type of pharmacophore multiplet used. 相似文献
5.
The equation of transfer for interlocked multiplets in anisotropically scattering atmosphere with planetary phase function has been considered. The Planck function is considered as exponential function of optical depth. The diffusely reflected intensity and emergent intensity in nth approximation has been obtained. Attempt has been made to get exact diffusely reflected intensity and emergent intensity. 相似文献
6.
Juan F. Espinosa Paloma Vidal Teodor Parella Sergi Gil 《Magnetic resonance in chemistry : MRC》2011,49(8):502-507
The SELective INverse detection of carbon–proton CORrelation pulse sequence that yields a 1D spectrum of a proton directly bonded to a selected carbon resonance has been converted into a proton and carbon double‐selective variant that provides a 1H spectrum of a selected proton that is long‐range coupled to a specific carbon resonance. The resulting 1D proton multiplet exhibits a pure absorptive in‐phase lineshape for precise measurement of specific long‐range proton–carbon coupling constants in small organic molecules at natural abundance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
Summary A kinetic energy analysis of total energy differences in atomic multiplets arising fromf
m (m=2–12) electronic configurations is performed within the nonrelativistic restricted Hartree-Fock framework. For these 1290 multiplets of 22 lanthanoid (Ce to Er) and actinoid (Th to Fm) atoms, a very good linear correlation between the total energy difference and the kinetic energy difference of the outermostf-electrons is found. The present results, together with our previous ones for the multiplets arising froms
mpn (m=1,2;n=2–4) ands
mdn (m=0–2;n=2–8) electronic configurations, demonstrate that the kinetic energy difference of electrons in open subshells is an excellent predictor of total energy differences among atomic multiplet states. 相似文献
8.
M. Resano L. Rello M. FlórezM.A. Belarra 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(5):321-328
This paper explores the potential of commercially available high-resolution continuum source graphite furnace atomic absorption spectrometry instrumentation for the simultaneous or sequential monitoring of various atomic lines, in an attempt to highlight the analytical advantages that can be derived from this strategy. In particular, it is demonstrated how i) the monitoring of multiplets may allow for the simple expansion of the linear range, as shown for the measurement of Ni using the triplet located in the vicinity of 234.6 nm; ii) the use of a suitable internal standard may permit improving the precision and help in correcting for matrix-effects, as proved for the monitoring of Ni in different biological samples; iii) direct and multi-element analysis of solid samples may be feasible on some occasions, either by monitoring various atomic lines that are sufficiently close (truly simultaneous monitoring, as demonstrated in the determination of Co, Fe and Ni in NIST 1566a Oyster tissue) or, alternatively, by opting for a selective and sequential atomization of the elements of interest during every single replicate. Determination of Cd and Ni in BCR 679 White cabbage is attempted using both approaches, which permits confirming that both methods can offer very similar and satisfactory results. However, it is important to stress that the second approach provides more flexibility, since analysis is no longer limited to those elements that show very close atomic lines (closer than 0.3 nm in the ultraviolet region) with a sensitivity ratio similar to the concentration ratio of the analytes in the samples investigated. 相似文献
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We consider a particle moving on a cone and bound to its tip by 1/r or harmonic oscillator potentials. When the deficit angle of the cone divided by 2π is a rational number, all bound classical orbits are closed. Correspondingly, the quantum system has accidental degeneracies in the discrete energy spectrum. An accidental SU(2) symmetry is generated by the rotations around the tip of the cone as well as by a Runge-Lenz vector. Remarkably, some of the corresponding multiplets have fractional “spin” and unusual degeneracies. 相似文献
10.
We analyze short and long multiplets which appear in the OPE expansion of chiral primary operators in N=4 Super Yang–Mills theory. Among them, higher spin long and new short multiplets appear having the interpretation in the AdS/CFT correspondence of string states and supergravity multiparticle states, respectively. We also analyze the decomposition of long multiplets under N=1 supersymmetry as a possible tool exploring other supersymmetric deformations of IIB string on AdS5×S5. 相似文献