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31.
Peter Scharfenberg 《Theoretical chemistry accounts》1985,67(3):235-243
Bromine parameters are proposed, matching well the standard values of first and second row atoms, as introduced by Pople et al. This is shown by comparisons of geometries, configurations, conformations, and dipole moments, obtained with different approaches. The new parameter set was found in a very simple and efficient way that may also be useful for other tasks, e.g. in non-empirical calculations. 相似文献
32.
Toshikatsu Koga 《Theoretical chemistry accounts》1989,75(6):417-424
Based on momentum- and position-space analyses of the moment operators for two-electron atoms, it is shown that there exists a family of two-electron wave functions which satisfy a proportionality relation, r/
1
v
/r
12
v
=p/
1
v
/p
12
v
=2–v/2, between the one and two-electron moments in position and momentum spaces, where v is an arbitrary number for which the moments are well-defined. 相似文献
33.
Karl Jug 《Theoretical chemistry accounts》1973,31(1):63-73
A new definition of atomic charges in molecules is presented which conserves charge and dipole moment. It contains the Mulliken and Löwdin definitions as special cases of zero and first order truncations of commutator expansions. The definition allows for a systematic improvement of charges paralleling the improvement of the basis set in the LCAO approximation. We have tested the definition in thirteen selected diatomics and polyatomics in optimal minimal Slater basis set SCF calculations by means of 4G-level Gaussian expansions. The results suggest that the proposed definition is better than either Mulliken's or Löwdin's definition.Presented in part at the E. U. Condon Symposium, Sanibel Island, Florida, 21–27 January 1973. 相似文献
34.
Summary Dipole Cauchy moments of the atoms through Ar are calculated using the hydrodynamic formulation of time-dependent Kohn-Sham theory. The exchange-correlation energy density functional is approximated by the gradient expansion for atoms. Using variational trial functions that contain both linear and nonlinear variational parameters, we are able to reproduce (to three or four significant figures) the static dipole polarizabilities obtained by explicitly solving the relevant differential equations. The resulting dipole Cauchy moments provide a convenient starting point for calculating other properties which result from the linear interaction of atoms with a time varying electric field. 相似文献
35.
The dipole moments of a number of substituted benzaldehydes are measured in benzene solution. The angle which the dipole axis
of the CHO group makes with the axis of rotation of the group is determined. The observed moments of the ortho-substituted
benzaldehydes are compared with the moments calculated for free rotation as well as fors-trans ands-cis orientations of the -CHO group.o-Fluorobenzaldehyde exists mostly in thes-trans conformation.o-Chloro-,o-bromo-ando-nitro-benzaldehydcs also exist in thes-trans conformation; their observed dipole moments are even lower than the values calculated fors-trans forms, indicating mutual induction of the ortho substituents. Though 2,5-dichlorobenzaldehyde is expected to have the same
dipole moment as benzaldehyde, the observed moment is significantly lower due to mutual induction of the ortho substituents.
2,5-Dimethylbcnzaldehyde has, however, almost the same moment as benzaldehyde. The dipole moment ofo-methoxybcnzaldchyde is considerably higher than the values calculated for boths-cis ands-trans conformations. An explanation is given for this.o-Hydroxybenzaldehyde exists exclusively in thes-cis form due to internal H-bonding. 相似文献
36.
Summary The first-order polarized basis sets for the use in high-level-correlated investigations of molecular electric properties have been generated for Pb, Bi, Po, and At. The performance of the standard [10.17.14.5/13.11.8.2] and extended [20.17.14.9/13.11.8.4] basis sets has been examined in nonrelativistic and quasirelativistic calculations for atoms and simple closed-shell hydrides. The relativistic contributions to electric dipole properties of those systems have been evaluated by using the recently developed quasirelativistic scheme. The predicted dipole polarizability of At is in good agreement with the results of other relativistic calculations. The calculated quasirelativistic dipole moments of BiH3 (–0.499 a.u.), PoH2 (–0.207 a.u.), and AtH (+0.036 a.u.) involve a significant relativistic contribution which amounts to —0.230 a.u., –0.177 a.u., and –0.097 a.u., respectively. The basis set details append this paper. They are also available as a part of the basis set library of the MOLCAS system. 相似文献
37.
Jean Diebolt 《Journal of Theoretical Probability》1991,4(4):655-667
We consider the Markov chainX
n+1=T(X
n
)+
n
, where {
n
;n1} is a
d
-valued random sequence of independent identically distributed random variables, and the functionT:
d
d
is measurable and satisfies a suitable growth condition. Under certain conditions involvingT and the probability distribution of
n
, we show that this Markov chain is ergodic. Moreover, we obtain sharp upper bounds for the tail of the corresponding stationary probability density function. In our proofs, we make use of the Leray-Schauder fixed-point theorem. 相似文献
38.
Summary The CHARGE2 program for the calculation of partial atomic charges has been amended to include bond parameters for a number of organic functional groups, including halogens, nitrogen and oxygen. These minor amendments to the original scheme produce dipole moments for the fluoro and chloro compounds which are in complete agreement with the observed values.The less complete data sets for the bromo and iodo compounds are also well reproduced, and the dipole moments of a variety of mixed halo compounds are now in better agreement with experiment than previously.The calculated dipole moments of the saturated nitrogen and oxygen compounds are now in much better agreement than in the original scheme, thus the revised parameterisation may be employed with confidence to predict the electrostatic energies of these compounds.Furthermore, the revised scheme now gives a precise proportionality between the charge on the proton in a CH group and the 1H chemical shift of the corresponding proton, allowing the general prediction, in principle, of 1H chemical shifts. In addition, attempts to include variable electronegativity in the effect are described for fluoro compounds.For part VIII see Ref. 1. 相似文献
39.
40.
Vaggelis Hondrellis Themistoclis Kabanos Spyros P. Perlepes John M. Tsangaris 《Monatshefte für Chemie / Chemical Monthly》1988,119(10):1091-1101
New complexes of the formulaeM(fur)2·2H2O (M = Mn, Cu, Zn),M(fur)2·3H2O (M = Co, Ni, Cd), Hg2(fur)3Cl2·2H2O, Pd(fur)Cl·H2O and Rh(fur)3·3H2O, wherefurH = 4-chloro-N-(2-furfuryl)-5-sulfamoylanthranilic acid, have been prepared and characterized by conductivity measurements, X-ray powder patterns, thermal methods, effective magnetic moments as well as by IR, ligand field,1H-NMR and ESR spectroscopic studies. The anionfur
– shows a chelated bidentate O(carboxylato), N(imino)-coordinating behaviour.
Metallkomplexe der diuretischen Droge Furosemid
Zusammenfassung Neue Komplexe der Verbindungen:M(fur)2·2H2O (M = Mn, Cu, Zn),M(fur)2·3H2O (M = Co, Ni, Cd), Hg2(fur)3Cl2·2H2O, Pd(fur)Cl·H2O und Rh(fur)3·3H2O, wobeifurH 4-chlor-N-(2-furfuryl)-5-sulfamoylanthanilsäure ist, wurden dargestellt. Die Komplexe wurden durch Leitfähigkeitsmessungen, Röntgen-Pulver-Aufnahmen, thermogravimetrische Analysen, Messungen des effektiven magnetischen Dipolemomentes sowie durch spektroskopische Untersuchungen (IR,1H-NMR und ESR) charakterisiert. Das Anionfur – zeigt das Verhalten einer Chelat-bidentat-O(carboxylato),N(imino)-Koordination.相似文献