共查询到20条相似文献,搜索用时 187 毫秒
1.
A. A. Buchachenko 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):291-296
The finite-field scalar relativistic coupled cluster and configuration
interaction, as well as the spin-orbit configuration interaction,
methods are employed to calculate the static dipole polarizabilities for the
lowest (6s
2) 1S, (6s6p) 1,3^{1,3}Po and (6s5d) 1,3^{1,3}D excited
states of atomic ytterbium. The results agree very well with existing
experimental and best
theoretical data and refine the set of ytterbium polarizabilities known so
far. Similar techniques are used to calculate the electric quadrupole moments
for the 1,3^{1,3}Po and 1,3^{1,3}D states. 相似文献
2.
The multi-configuration Dirac-Fock(MCDF) method is implemented to study doubly excited 2s2p 1,3P1 resonances of the helium atom and the interference between photoionization and photoexcitation autoionization processes.In order to reproduce the total photoionization sprectra,the excited energies from the ground 1s2 1S0 state to the doubly excited 2s2p 1,3P1 states and the relevant Auger decay rates and widths are calculated in detail.Furthermore,the interference profile determined by the so-called Fano parameters q and ρ2 is also reproduced.Good agreement is found between the present results and other available theoretical and experimental results.This indeed shows a promising way to investigate the Fano resonances in photoionization of atoms within the MCDF scheme,although there are some discrepancies in the present calculations of the 2s2p 3P1 state. 相似文献
3.
We have investigated the doubly excited 1,3
P
e resonance states of positronium negative ion with Coulomb and screened Coulomb potentials using highly accurate correlated
exponential wavefunctions. For Coulomb interaction, the stabilization and the complex-rotation methods are employed to extract
resonance parameters (resonance positions and widths). We have obtained two 1
P
e resonances and three 3
P
e resonances below the n = 3 Ps threshold. In addition to Feshbach resonances lying below n = 3 Ps threshold, we have calculated one 3
P
e shape resonances lying above the Ps (n = 2) threshold. For screened Coulomb (Yukawa) interaction, we employ the stabilization method to extract resonance parameters
as functions screening parameter. The resonance energies and widths for 1,3
P
e resonance states of Ps− below the n = 3 Ps threshold for different screening parameters ranging from infinity (Coulomb case) to small values are reported, along
with the Ps(3S) and Ps(3P) threshold energies. The screened Coulomb results for the 1,3
P
e resonance states are reported for the first time in the literature. 相似文献
4.
5.
Using the modified Feshbach method, the1,3Se,1,3Po,1,3De,1,3So autoionization states of the beryllium atoms are calculated in the region of the first ionization threshold. The energies and widths of the autoionization states of Be are obtained. The results obtained are compared with experimental data and the results of existing theoretical calculations. The good agreement between the results obtained and the experimental data and other theoretical calculations is pointed out.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 23–28, March, 1984. 相似文献
6.
Vikas Tayal G. P. Gupta 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):449-457
Excitation energies from ground state for 86 fine-structure levels as well
as oscillator strengths and radiative decay rates for all fine-structure
transitions among the levels of the terms
(1s22s22p6)3s2(1S), 3s3p(1,3Po),
3s3d(1,3D), 3s4s(1,3S), 3s4p(1,3Po), 3s4d(1,3D),
3s4f(1,3Fo), 3p2(1S, 3P, 1D),
3p3d(1,3Po, 1,3Do, 1,3Fo),
3p4s(1,3Po), 3p4p(1,3S, 1,3P, 1,3D),
3p4d(1,3Po, 1,3Do, 1,3Fo), 3p4f(1,3D,
1,3F, 1,3G) and 3d2(1S, 3P, 1D, 3F,1G) of Cr
XIII are calculated using extensive configuration-interaction
(CI) wave functions obtained with the CIV3 computer code of Hibbert. The
important relativistic effects in intermediate coupling are included through
the Breit-Pauli approximation via spin-orbit, spin-other-orbit, spin-spin,
Darwin and mass correction terms. Small adjustments to the diagonal elements
of the Hamiltonian matrices have been made. The mixing among several
fine-structure levels is found to be very strong. Our excitation energies,
including their ordering, are in excellent agreement (better than 0.5%)
with the available experimental results. From our transition probabilities,
we have also calculated radiative lifetimes of some fine-structure levels.
Our calculated lifetime for the longer-lived level 3s3p(3P1) is
found to be in excellent agreement with the experimental result of Curtis
compared to other theoretical calculations. 相似文献
7.
I. G. Ivanov 《Journal of Russian Laser Research》2003,24(1):27-36
Results of theoretical and experimental studies of the behavior of the level populations and gain factors for the np
1,3
P – ns
1,3
S and np
1,3
P –>
(n-1)d
1,3
D transitions in Tl II (n = 7) and Ga II (n = 5) are presented. These levels are filled due to the charge exchange in thermal collisions of neon ions with thallium and gallium atoms in thallium--neon and gallium--neon mixtures, respectively. The total pumping rate of all levels of a metal due to the charge exchange in the hollow-cathode discharge plasma at the operating concentrations of metal vapors was shown to be equal to the gas ionization rate. The latter is defined by the number of fast electrons and is independent of the charge-exchange cross section. The exciting and deexciting collisions with slow electrons and gas atoms were taken into account for all Tl II and Ga II levels related to the laser ones, and the radiation trapping by the resonance transitions of metal ions was considered. The partial pumping rates by the charge exchange were found for levels with 0 < E() < 1.5 eV. Theoretical results are compared with experimental data. The behavior of the lasing characteristics is explained for the known laser transitions. The parameters of the as yet unknown transitions in the IR range are predicted. 相似文献
8.
C. Chen B. C. Gou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):545-550
The hyperfine structure parameters of the 1s22snp (n=2, 3) 3P states for the beryllium isoelectronic sequence from Z= 4 to 10 are calculated with the full-core plus correlation (FCPC)
wave functions. For the 1s22s2p 3P state of the beryllium atom, the calculated fine structure parameters are in good agreement with the latest theoretical
and experimental data in the literature. It is shown that hyperfine constants of the low-lying excited states for the beryllium
atom can be calculated accurately using this theoretical method. For 1s22snp (n=2, 3) 3P states of the beryllium isoelectronic sequence, our predictions may provide valuable reference data for other theoretical
calculations and experimental measurements in future. 相似文献
9.
利用基于多组态Dirac-Fock理论方法的研究原子结构和性质的程序GRASP92和RATIP以及最新发展的研究光电离和辐射复合过程的程序RERR06,研究了光子能量为947.9 eV时Ne原子的1s光电子谱及其相应的Auger衰变过程.所得结果与其他的理论结果和实验结果符合得很好.通过分析光电离伴随态Ne+1s-12p-1(1,3P)3p的Auger衰变过程可知:3p旁观的Auger跃迁是主要的衰变机制,Ne+1s-12p-1(1P)3p的Auger强度整体上大于Ne+1s-12p-1(3P)3p的Auger强度.同时,也预言了光电离伴随态Ne+1s-12p-1(1,3P)3p产生的Ne+,Ne2+和Ne3+末电离态离子的相对丰度分别为0.02,0.58和0.41.
关键词:
光电离
Auger衰变
多组态Dirac-Fock方法 相似文献
10.
By using crystal-field theory, the optical spectra and spin-Hamiltonian parameters (abbr. SH parameters, i.e. the anisotropic
g factors g
∥ , g
⊥ , and hyperfine structure constants A
∥ , A
⊥ ) of 171Yb3 + and 173Yb3 + isotopes in the tetragonal PbWO4 are calculated. The theoretical results agree well with the experimental values. The crystal-field parameters and the signs
of the hyperfine structure constants for both 171Yb3 + and 173Yb3 + isotopes are determined. The validities of the theoretical results are discussed. 相似文献
11.
Configuration interaction calculations have been carried out on electronic states of the CsLi molecule and the CsLi+ cation. Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels are presented for the
lowest states of 1,3Σ+, 1,3Π, and 1,3Δ symmetries of the alkali dimer CsLi molecule dissociating into Cs (6s, 6p, 5d, 7s, and 7p) + Li (2s, 2p, 3s, 3p, and 3d)
as well as for the lowest 2Σ+, 2Π, and 2Δ electronic states of the CsLi+ cation dissociating into Li (2s, 2p, 3s, 3p, and 3d) + Cs+ and Li+ + Cs (6s, 6p, 5d, 7s, and 7p). The results of the present many-electron configuration interaction calculations on the cation
support the previous core-polarization effective potential calculations. The present calculations on the CsLi molecule are
complementary to previous theoretical work on this system, including recently observed electronic states that had not been
calculated previously. We have used an ab initio approach involving a nonempirical pseudopotential for the Li (1s2) and Cs cores and a core-valence correlation correction. A very good agreement of data from spectroscopic constants for some
of the lowest states of the CsLi and CsLi+ molecules with those available in recent theoretical works has been obtained. The existence of numerous avoided crossings
between electronic states of 2Σ+ and 2Π symmetries is related to a charge transfer process between the two ionic CsLi+ and LiCs+ systems. 相似文献
12.
The fine structure theory of 3Σ states in diatomic molecules is re-examined with particular emphasis on centrifugal distortion in the triplet splitting parameters. The theoretical results are compared with optical and microwave data for the 3Σ ground states of O2 and SO. Excellent agreement is found between theoretical predictions and experimental results concerning the centrifugal distortion in the spin-spin splitting for both O2 and SO. However, in contrast to ab initio calculations this agreement indicates that the second-order contribution to the spin-spin splitting is of minor importance. The theoretical value of the centrifugal distortion in the spin-rotation coupling constant is about twice the experimental one for O2. It is pointed out that a slight transition towards coupling case (c) yields a reasonable explanation for this discrepancy. 相似文献
13.
分别用PW91,B3LYP两种密度泛函方法和全电子高斯基组对β-Si3N4的几何结构进行全优化(包括晶格参数和原子坐标),结果和实验值符合良好. 同时计算了能带结构和态密度.在此基础上分别用上述两种方法计算了Γ点拉曼振动频率,并按对称性进行分类,将得到的11种拉曼活性模式的频率值与实验值以及其他文献值进行了比较,进一步确定了Ag模式为中等频率,值约459cm-1. 计算结果表明
关键词:
振动频率
密度泛函理论
电子结构
3N4')" href="#">β-Si3N4 相似文献
14.
A method is developed for the semiempirical calculation of fine structure parameters from the experimental energy intervals
between magnetic sublevels. The calculations are performed using the configuration of neutral carbon as an example. The calculated
parameters are used to calculate the 2p
2 configuration energy spectrum and the gyromagnetic ratios of the 3
P
2 and 1
D
2 levels, as well as the magnetic splitting of triplet levels. The results are compared with available experimental and theoretical
data. It is confirmed that the dependence of the energy of magnetic sublevels of np
2 configurations on the magnetic induction is parabolic for sublevels with the projections M = 0, ±1 and is linear for sublevels with M = ±2. 相似文献
15.
16.
The influence of Debye potentials on the quadrupole oscillator strengths of helium atom is investigated using highly correlated wave functions within a framework of a variational method. The quadrupole oscillator strengths for the 1,3S–1,3D, 1,3P–1,3P and 1,3D–1,3D transitions of He for various screening parameters are reported for the first time in the literature. In free atomic case, our calculated results are in good agreement with the available results. 相似文献
17.
18.
To better clarify the physical properties for Al3RE precipitates, first-principles calculations are performed to investigate the vibrational, anisotropic elastic and thermodynamic properties of Al3Er and Al3Yb. The calculated results agree well with available experimental and theoretical ones. The vibrational properties indicate that Al3Er and Al3Yb will keep their dynamical stabilities with L12 structure up to 100 GPa. The elastic constants are satisfied with mechanical stability criteria up to the external pressure of 100 GPa. The mechanical anisotropy is predicted by anisotropic constants AG, AU, AZ and 3D curved surface of Young’s modulus. The calculated results show that both Al3Er and Al3Yb are isotropic at zero pressure and obviously anisotropic under high pressure. Further, we systematically investigate the thermodynamic properties and provide the relationships between thermal parameters and pressure. Finally, the pressure-dependent behaviours of density of states, Mulliken charge and bond length are discussed. 相似文献
19.
Svetlana V. Kirpichenko Bagrat A. Shainyan Erich Kleinpeter 《Journal of Physical Organic Chemistry》2012,25(12):1321-1327
The conformational analysis of the first representative of the Si‐alkoxy substituted six‐membered Si,N‐heterocycles, 1,3‐dimethyl‐3‐isopropoxy‐3‐silapiperidine, was performed by low‐temperature 1H and 13C NMR spectroscopy and DFT theoretical calculations. In contrast to the expectations from the conformational energies of methyl and alkoxy substituents, the Meaxi‐PrOeq conformer was found to predominate in the conformational equilibrium in the ratio Meaxi‐PrOeq : Meeqi‐PrOax of ca. 2 : 1 as from the 1H and 13C NMR study. The thermodynamic parameters obtained by the complete line shape analysis showed that the main contribution to the barrier to ring inversion originates from the entropy term of the free energy of activation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
The acetone molecule is investigated in its ground state and valence 1,3n-π*, 1,3π-π*, and 1,3σ-π* excited states and Rydberg 1,3n-3s, 1,3π-3?, 1,3n-3py and 1,3π-3py states using the CASSCF, CASPT2, and CCSD(T) methods. Equilibrium geometries of excited states are obtained and their changes with respect to the ground state are discussed. For most excited states the C2v symmetry of the ground state is lowered to the Cs symmetry. A series of valence vertical and adiabatic excitation energies is presented along with excitation energies for Rydberg states. The main body of the paper contains Finite-Field Perturbation Theory (FFPT) calculations of electric properties of the vertically as well as geometry relaxed excited states. Dipole moments of valence excited states decrease significantly upon excitation, being about one half of the ground state dipole moment. Polarizabilities usually change upon excitation much less (increase by about 30%) but hyperpolarizabilities are enhanced up to one or two orders of magnitude. The orientation of the dipole moment is reversed in some vertically excited Rydberg states. Properties of the ground and excited states are discussed considering alterations of the electronic structure and shifts in the geometry. 相似文献