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Møller Jesper Christensen Heidi S. Cuevas-Pacheco Francisco Christoffersen Andreas D. 《Methodology and Computing in Applied Probability》2021,23(2):569-591
Methodology and Computing in Applied Probability - This paper concerns space-sphere point processes, that is, point processes on the product space of $\mathbb {R}^{d}$ (the d-dimensional Euclidean... 相似文献
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J. D. Petke Gerald M. Maggiora Lester L. Sipman Ralph E. Christoffersen 《Photochemistry and photobiology》1981,33(5):663-671
Abstract— Ab initio configuration interaction wavefunctions and energies are reported for 19 doublet states of the anion radical of ethyl bacteriochlorophyllide a (Et-BChl a˙), and are employed in a resolution of the electronic absorption spectrum, as well as in a comparison with a previously reported study of the electronic states and spectrum of the anion radical of ethyl bacteriopheophorbide a (Et-BPheo a˙). The lowest two excited doublet states, D1 and D2, of Et-BChl a˙ are found to be approximately degenerate and are predicted to contribute to the experimentally observed absorption at 10000 cm?1. In contrast, the D2←D0 transition in Et-BPheo a˙ is predicted to contribute to the 11000 cm?1 absorption, while the D1←D0 transition appears at approximately 8600 cm?1 with a low oscillator strength (f= 0.002). The prominent visible absorption at ~15700 cm?1 in both molecules is found to be due to the D4← D0 transition. Another difference between the predicted spectra of the two molecules appears in the low-energy shoulder of the Soret band. Here, two intense transitions, D10←D0 and D11←D0, are predicted for Et-BChl a˙, as opposed to three fairly intense transitions, D7←D0, D8←D0 and D9←D0, for Et-BPheo a˙, differences which may provide a means of distinguishing between the two molecules using resonance Raman spectroscopy. The remainder of the Soret band of Et-BChl a˙ above 26000 cm?1 consists of a number of closely-spaced transitions to states D12←D18. The intense transitions D12←D0, D13←D0, D14←D0 are predicted to contribute to the Soret maximum near 30000 cm?1. The ground state spin densities of the two molecules are similar, with the minor difference of somewhat less spin density located on the methine carbon atoms of Et-BChl a˙ compared with Et-BPheo a˙. 相似文献
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An exact solution is obtained for the one-dimensional time-independent Schrödinger equation with a symmetric double minimum potential constructed from two Morse potentials. This model potential is used to describe the inversion motions in NH3, ND3, and NT3, and its adequacy is discussed. 相似文献
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Dale Spangler Ralph E. Christoffersen 《International journal of quantum chemistry》1980,17(6):1075-1097
By determining basis set parameters in molecular environments using other criteria than total energy, it is shown that a generalization of the molecular fragment basis can be obtained in which calculated geometric and electronic structural properties are predicted substantially better than with other basis sets of similar size. As a first step in the development of a series of basis sets having successively greater flexibility and accuracy, several single-zeta basis sets are created, using a two-Gaussian contraction for each basis orbital. The best of these basis sets produced calculated geometric and electronic properties for a series of molecules that model a wide variety of organic molecules that are of better accuracy than the corresponding STO -2G basis, and similar in most cases to STO -3G. In addition, the basis set is shown to be applicable in either a Cartesian Gaussian basis or a floating spherical Gaussian basis. 相似文献
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Thostrup P Christoffersen E Lorensen HT Jacobsen KW Besenbacher F Nørskov JK 《Physical review letters》2001,87(12):126102
Through an interplay between density functional calculations, Monte Carlo simulations and scanning tunneling microscopy experiments, we show that an intermediate coverage of CO on the Pt(110) surface gives rise to a new rough equilibrium structure with more than 50% step atoms. CO is shown to bind so strongly to low-coordinated Pt atoms that it can break Pt-Pt bonds and spontaneously form steps on the surface. It is argued that adsorption-induced step formation may be a general effect, in particular at high gas pressures and temperatures. 相似文献
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J. D. Petke Gerald M. Maggiora Lester L. Shipman† Ralph E. Christoffersen 《Photochemistry and photobiology》1980,32(5):661-667
Ab initio configuration interaction wavefunctions and energies are reported for 16 doublet states of the anion radical of ethyl bacteriopheophorbide a (Et-BPheo a-˙), and are employed in an analysis of the electronic absorption spectrum. The lowest excited doublet state D1 is predicted to lie 8601 cm-1 above the ground state D0; the D1← D0 transition is nearly forbidden, with a computed oscillator strength f= 0.002. The visible absorption spectrum is shown to consist of transitions to three 2(π, π*) states, D2, D3, and D4. The D4← D0 transition (y-polarized, f= 0.91) appears to account for observed intense absorption at 15 800 cm-1. The Soret band of Et-BPheo a-˙ is shown to consist of transitions to several 2(π,π*) states, D7-D15. Transitions of particularly high intensity include D7← D0 (y-polarized, f= 0.72), D10← D0 (y-polarized, f= 1.1), D12← D0 (xy-polarized, f= 0.86) and D15← D0 (y-polarized, f= 0.83). Spin density data and plots are used to describe and compare the general features of the unpaired spin distributions in D0 and D1, which are in reasonable agreement with other reported calculated values and available experimental data for D0. 相似文献
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Fifteen patients with liver cirrhosis and two control groups were examined. The first control group consisted of 7 healthy volunteers, and the second group of 17 patients with nonfocal liver diseases. The T1 and T2 relaxation times were calculated from signal intensities read out from a region of interest centrally located in the liver. T1 relaxation time was longer in the patients with liver cirrhosis than in the two reference groups. Ten patients had a liver biopsy taken prior to the MRI study. No correlation was found between histopathology and the measured relaxation times. 相似文献
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