Effects on spectroscopic properties for several low-lying electronic states of CS molecule by core-valence correlation and relativistic corrections

The potential energy curves (PECs) of six low-lying electronic states (X¹Σ⁺, a³Π, a′³Σ⁺, d³Δ, e³Σ⁻ and A¹Π) of CS molecule have been investigated using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach with large correlation-consistent basis sets. Effects on the PECs by the core-valence correlation and relativistic corrections have been taken into account. And the two corrections are performed at the level of cc-pV5Z basis set. The way to consider the relativistic corrections is to use the second-order Douglas-Kroll Hamiltonian approximation. Using the CCSD(T), MRCI and MRCI with the Davidson modification (MRCI + Q), the PECs of electronic states involved are extrapolated to the complete basis set (CBS) limit. With the PECs, the spectroscopic parameters (T_e, R_e, ω_e, ω_ex_e, ω_ey_e, α_e, β_e, γ_e and B_e) of the six low-lying electronic states are determined. These parameters are in excellent agreement with the experimental data. The complete vibrational states are computed for the six low-lying electronic states when the rotational quantum number J equals zero, and the inertial rotation constants of the first 23 vibrational states are reported, which agree favorably with the RKR data. Comparison with the measurements shows that the two-point total-energy extrapolation scheme can obviously improve the quality of spectroscopic parameters and molecular constants.     

Composition dependence of effective thermal conductivity and effective thermal diffusivity of Se100−xInx (x=0, 5, 10, 15 and 20) chalcogenide glasses

Simultaneous measurement of effective thermal conductivity (λ_e) and effective thermal diffusivity (χ_e) of twin pallets of Se_100−xIn_x (x=0,5, 10, 15, and 20) glasses, prepared under a load of 5 tons, have been made at room temperature using the Transient Plane Source (TPS) technique. The values of λ_e and χ_e were found to increase initially with the increase of concentration of In in Se-In alloy and had their maximum at 10 at.wt% of indium. For indium concentration beyond 10 at.wt% of the values of effective thermal conductivity and effective thermal diffusivity decrease linearly. This is suggestive of fact that 10 at.wt% of indium can be considered as a critical composition at which the alloy becomes, chemically ordered and maximum thermally stable than other composition. Further addition of indium in selenium decreases the values of λ_e and χ_e. The behaviour is explained on the basis of decrease of localized states and increase in disorderness for higher composition indium.     

The reversal of magnetization driven by the Dzyaloshinskii-Moriya interaction in Bi2FeMnO6

Ab initio calculations show that the coupling between antiferrodistortive (AFD) distortions and magnetization in perovskite Bi₂FeMnO₆ is prohibited to make magnetization rotate as effective Hubbard parameter is larger than 2.7 eV, where anomalies in antiferromagnetic (AFM) vectors and band gap varying with on-site Coulomb interaction can be observed. This coupling is attributed to the antisymmetric Dzyaloshinskii-Moriya interaction driven by the e_g-e_g states AFM interaction and charge redistribution with respect to different AFD distortions.     

Collective states in 48V

The low-lying positive parity states of ⁴⁸V have been studied in the framework of deformed configuration mixing model calculations based on projected Hartree-Fock theory, within the full fp shell space. The modified Kuo-Brown effective interaction has been used. The calculated spectrum and the electromagnetic properties of these states are in good agreement with the experiment. The calculation predicts an excited low-lying collective K = 2⁺ band in the spectrum of ⁴⁸V and accounts for the observed breakdown of the “signature” selection rule arising in the shell-model calculation within the ($\text{f}\text{7}\text{2}\text{)}{}^{\mathrm{nd}}$ space. It does not favour a 5⁺ assignment to the observed 1.099 MeV level. Two sets of proton and neutron effective charges (i) e_p = 1.32e and e_n = 0.89e and (ii) Kuo and Osnes charges e_p = 1.25e and e_n = 0.47e were employed. The observed decay properties appear to favour the latter charges. Our model also explains in a semiquantitative way the observed K-value, moment of inertia parameter and the intrinsic quadrupole moment of the K = 1^?1 rotational band.     

Comparison of e+e− annihilation with QCD and determination of the strong coupling constant

We have analyzed 1113 events of the reaction e⁺e^? → hadrons at CM energies of 12 and 30 GeV in order to make a detailed comparison with QCD. Perturbative effects can be well separated from effects depending on the quark and gluon fragmentation parameters to yield a reliable measurement of the coupling constant α_S. At 30 GeV, the result is α_S = 0.17 ± 0.02 (statistical) ± 0.03 (systematic). QCD model predictions, using the fragmentation parameters determined along with α_S, agree with both gross properties of the final states and with detailed features of the three-jet states.     

χ particle production in π−p collisions at 38 GeV/c

The production of χ particles in the reaction π^?p → χ + … has been studied near threshold. The measurements have been performed at the 70 GeV IHEP proton synchrotron using the hodoscope spectrometer GAMS-2000. The χ particles have been identified through their decay χ → J/ψ + γ, J/ψ → e⁺e^?. In the region X_F ?0.4 the fraction of obsered J/ψ particles which is obtained via the decay of χ states is 0.44 ± 0.16. The χ longitudinal and transverse momentum distributions are similar to those obtained for J/ψ. The inclusive production cross section of χ particles (³P₁ and ³P₂ states) at 38 GeV/c is σ_XF>0 (π^?p → χ + …) = (28±11) nb.     

Vibrational analysis of the a3Σ+-X1Σ+ and b3Π-X1Σ+ band systems of GeS

Spectra of GeS have been obtained in a chemiluminescent flame produced by the reaction Ge + OCS → GeS + CO. Neither of the known band systems, D¹Π-X¹Σ⁺ and E¹Σ⁺-X¹Σ⁺, was observed, but two new band systems in the regions 350–400 and 420–650 nm were obtained. By comparison with similar systems in isovalent molecules, these were assigned as b³Π₁-X¹Σ⁺ and a³Σ⁺-X¹Σ⁺, respectively. Vibrational assignments were made with the help of the germanium isotope effect and vibrational constants were obtained for the states involved. Approximate Morse potential Franck-Condon factors were computed and were shown to fit the general trend of the intensity distribution for both systems. Addition of active nitrogen to the flame was shown to increase the intensity of the b-X system by an order of magnitude while hardly affecting the a-X system. Constants (in cm^?1) obtained for the two new states are: a³Σ⁺: T_e = 21986.3 ± 2.3, ω_e = 388.9 ± 1.0, ω_ex_e = 1.35 ± 0.11; b³Π₁: T_e = 27192.0 ± 1.8, ω_e = 435.4 ± 1.1, ω_ex_e = 1.68 ± 0.20.     

Equilibrium structure and anharmonic potential function of phosgene: Diode laser spectra of the ν1 and ν5 bands

The vibration-rotation spectra of the ν₁ and ν₅ bands of phosgene (³⁵Cl₂CO) were measured and analyzed with the aid of Stark modulation spectra for assignment of complicated spectral features. The rotational constants for the ν₁ state were determined to be A₁ = 7885.65(17), B₁ = 3470.25(9), and C₁ = 2406.85(9) MHz. They were used with the ones for the ν₂ ～ ν₆ states reported previously for derivation of the equilibrium rotational constants of ³⁵Cl₂CO: A_e = 7950.35(22), B_e = 3490.22(11), and C_e = 2425.44(22) MHz.     

Potential energy curves for the 48 lowest-lying molecular states of LiH+

The electronic energies of the 20 lowest lying ²Σ⁺ states, the 14 lowest lying ²Π states, and the 14 lowest lying ²Δ states of LiH⁺ have been calculated in the range 2 ≤ R ≤ 20 a.u. from a model potential approach and using truncated diatomic orbitals (TDO) as basis set. Results in very good agreement with the more recent literature were obtained for the spectroscopic constants, R_e and D_e, for the ground state X²Σ⁺.     

Submillimeter-wave spectroscopy of HN2 and DN2 in the excited vibrational states

The pure rotational transitions of HN₂⁺ and DN₂⁺ in the first excited vibrational states for all the fundamental vibrational modes have been observed in the range of 300-750 GHz. The molecular constants determined are much more accurate compared with those obtained from the infrared spectroscopy. The equilibrium rotational constants, B_e = 46832.45 (71) MHz for HN₂⁺ and B_e = 38708.38 (58) MHz for DN₂⁺, have been determined by correcting for the higher-order vibration-rotation interaction effects, γ_ij, obtained by an infrared investigation. The equilibrium bond lengths are derived from these equilibrium rotational constants: r_e(H-N) = 1.03460 (14) Å and r_e (N-N) = 1.092698 (26) Å.     

Laser magnetic resonance for the v = 1 ← 0 transition of SeO (X3Σ−) by a CO2 laser

The vibration-rotation transitions for a fundamental band of SeO (X³Σ^?) were studied by means of the infrared laser magnetic resonance (LMR) method employing a CO₂ laser. The LMR spectra arising from five SeO isotopic species except ⁷⁴SeO were detected and analyzed. Band origins for these species were determined. Molecular parameters ω_e, ω_eχ_e, B_e, and α_e, were obtained with the aid of the reduced mass relations. For ⁷⁷SeO the axial component of magnetic hyperfine interaction was obtained.     

High-resolution Fourier spectrometry of 14N2 and 15N2 infrared emission spectrum: Extensive analysis of the W3Δu - B3Πg system

The infrared spectrum of the nitrogen molecule, excited in a microwave discharge, has been recorded in high resolution by Fourier spectrometry in the range 2500–15 000 cm^?1. The precision of the measurements is estimated to be about 0.003 cm^?1. We have analyzed 19 bands of the W³Δ_u-B³Π_g system of ¹⁴N₂, with 0 ≤ v′ ≤ 7, and three bands of ¹⁵N₂ lying between 2500 and 5900 cm^?1. The molecular constants of the ³Δ_u and B³Π_g states have been determined by direct approach using an iterative nonlinear least-squares procedure. It has proved convenient to describe the levels of W³Δ_u state in a case a basis although in fact they approximate those of Hund's case b. Derived values of equilibrium constants of W³Δ_u are, in cm^?1: T_e = 8875.3347 (with origin taken in A, ³Σ_u⁺v = 0 level); ω_e = 1506.4859; ω_eχ_e = 12.5469; B_e = 1.4702537; α_B = 0.0170389; D_e = 0.55958 × 10^?5. RKR potential energy curves for the two states are constructed, and the Franck-Condon factors calculated for the W-B system.     

Radiative decay ofJ/ψ into γ π+ π−

The radiative decayJ/ψ → γ π⁺ π^? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe ⁺e^? storage rings at Orsay. The π⁺ π^? mass spectrum shows a cleanf ₂ (1270) signal, and the possible presence of two other states at thef ₂ (1720) andf ₄ (2030) masses. For thef ₂ (1270), the branching ratio BR(J/ψ →γf)xBR(f→π⁺ π^?) is measured to be (7.50±0.30±1.12)×10^?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed.     

MRCI study on spectroscopic and molecular properties of several low-lying electronic states of the CN radical

The potential energy curves (PECs) of eight low-lying electronic states (X²Σ⁺, A²Π, B²Σ⁺, a⁴Σ⁺, D²Π, E²Σ⁺, 1²Σ⁻ and F²Δ) of the CN radical have been studied using the ab initio quantum chemical method. The calculations have been performed using the complete active space self-consistent field (CASSCF) method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with the correlation-consistent basis sets of Dunning and co-workers. The effects on the PECs by the core-valence correlation and relativistic corrections are taken into account. The way to consider the relativistic correction is to use the second-order Douglas-Kroll Hamiltonian approximation. The core-valence correlation correction calculations are performed with the cc-pCVQZ basis set. The relativistic correction is carried out at the level of cc-pV5Z basis set. In order to obtain more reliable results, the PECs determined by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI+Q). The PECs are extrapolated to the complete basis set (CBS) limit by the total-energy extrapolation scheme. With these PECs, the spectroscopic parameters (T_e, R_e, ω_e, ω_ex_e, ω_eу_e, B_e, α_e and γ_e) are determined and compared with those reported in the literature. Finally, with the PECs obtained by the MRCI+Q/CV+DK+Q5 calculations, the complete vibrational states are computed for the eight electronic states by solving the ro-vibrational Schrödinger equation for the non-rotating radical, and the vibrational levels and inertial rotation and centrifugal distortion constants of the first 11 vibrational states are reported, which agree favorably with the available experimental data. The spectroscopic parameters of 1²Σ⁻ and F²Δ electronic states obtained by the MRCI+Q/CV+DK+Q5 calculations should be good predictions for future laboratory experiments.     

Spin-orbit effects in the ground X2Π state and two low-lying excited valence states B2Π and L′2Φ for NO

The potential energy curves and spectroscopic constants B _e , ω _e , ω _e χ _e , α _e , D _e of the six Ω states (X ²Π_1/2, ? 3/2, B ²Π_1/2, ? 3/2 and L ^′2Φ_{5/2,   7/2}) of the NO radical molecule were calculated using spin-orbit multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). The spin-orbit coupling effect was considered via the state interaction approach with the full Breit-Pauli Hamiltonian. The spin-orbit splitting energy between the X ²Π_1/2 and X ²Π_3/2 states of the NO radical is 129.61 cm^-1, which agrees reasonably well with the experimental value of 123.13 cm^-1. For the B ²Π_{1/2,   3/2} states, the spin-orbit coupling (SOC) splitting energy is 35.99 cm^-1, the corresponding experimental value is 31.7 cm^-1. The SOC splitting value of the L ^′2Φ_{5/2,   7/2} states was calculated to be 103.2 cm^-1. The spectroscopic constants R _e , ω _e , ω _e χ _e , B _e , α _e , D _e are in reasonable agreement with available experimental and theoretical data for the six Ω states.     

Elimination of the mott interband s-d enhancement of the electrical resistance of nickel and platinum owing to the excitation of electrons by femtosecond laser pulses

The dependence of electrical, σ, and thermal, κ, conductivities of metals on the electron temperature T _e at high (～1 eV) T _e values has been calculated. The two-temperature states for which the temperature T _e of heated electrons exceeds the temperature T _i of ions in the crystal lattice result from the excitation of electrons by femtosecond laser pulses. It is well known that the existence of empty d levels with a high density of states near the Fermi surface (as, e.g., in nickel, platinum, and iron) leads to a pronounced enhancement of the electrical resistance (Mott, 1936). This is due to an increase in the statistical factor related to the electron transitions to the empty states induced by collisions with phonons. It is found that the excitation of the electron subsystem significantly reduces the electron-phonon scattering to unoccupied d states since the chemical potential μ(T _e ) rises above the upper edge of the d band. The decrease in the scattering probability leads to the anomalous behavior of the conductivity σ_el-ph, which increases with the temperature T _e . Such a behavior turns out to be inverse with respect to the usual situation in condensed matter.     

The differential coefficient (∂P/∂n)ne for properties of diatomic molecules and atoms

The coefficient (?P/?n)_ne, where n is the stage of ionization and n_e is the total number of electrons, has been investigated for atoms and for diatomic molecules by the use of tabulated data. The P are (a) orbital configurations, (b) state symbols, (c) ionization potentials, (d) internuclear separations of ground state molecules, (e) crystal radii of ionized atoms, (f) relativistic HF radii of neutral atoms, (g) dissociation potentials of molecules, and (h) the logarithms of the transition moments of electron transitions from the first excited to the ground states of atoms and molecules. The differentials for atoms in cases (a), 0870 0891 V (c) and (h) add to form those for the diatomic molecules, agreeing with a prediction based on the matrix formulation of the periodic system of diatomic molecules diatomic molecules.     

Electric moments of the first excited state of 18O

The static quadrupole moment Q_2⁺ and the B(E2; 0⁺ → 2⁺) value of the first excited state of ¹⁸O at e_x = 1.982 MeV have been determined using the reorientation effect in Coulomb excitation. Surface-barrier detectors at laboratory angles of 90° and 174° were used to detect ¹⁸O ions elastically and inelastically scattered from ²⁰⁸Pb. At both angles, we determined experimentally the maximum bombarding energies at which nuclear interference effects were negligible. It is found that Q_⁺ = ?0.023 ± 0.021 e · b (?0.052 ± 0.021 e · b) for destructive (constructive) interference from higher states. This result is in good agreement with theoretical expectation. For the transition moment we find B(E2; 0⁺ → 2⁺) = 0.00390 ± 0.00018 e² · b² (0.00371 ± 0.00018 e² · b²) for destructive (constructive) interference.     

Li2分子自旋一致激发态a3Σ+u和b3Πu的分析势能函数的从头算

使用对称性匹配簇-组态相互作用方法首次计算了Li₂分子自旋一致激发态a³Σ⁺_u和b³Π_u的离解能、平衡几何及其谐振频率。使用最小二乘法、利用Murrell-Sorbie函数形式拟合出了Li₂分子三重态的第一激发态a³Σ⁺_u 和第二激发态b³Π_u的完整势能函数，并计算了这两个态的光谱常数 (B_e, α_e, ω_e 和 ω_eχ_e) 和力常数 (f₂, f₃和f₄)。得到了Murrell-Sorbie函数形式既适用于基态、又适用于激发态的结论。将计算得到的激发态（a³Σ⁺_u和b³Π_u）的离解能、平衡几何及其谐振频率与实验结果及其它理论计算结果进行了比较。从比较的结果中可以清楚地看出，本文的计算结果在计算精度方面有很大的改进。     

7Li2分子23Πu激发态的解析势能函数、振动能级及其转动惯量

使用Gaussian 03程序包中的“对称性匹配簇-组态相互作用”方法、在0.13—2.0nm的核间距范围内利用6-311+〖KG-*3〗+G(d,p)基组对⁷Li₂(2³Π_u)分子的势能曲线进行了计算, 同时使用最小二乘法将计算结果拟合成了解析势能函数. 利用拟合出的解析势能函数并结合Rydberg-Klein-Rees方法, 计算了该态的谐振频率, 进而计算了该态的其他光谱常数, 分别为T关键词： 解析势能函数 谐振频率 振动能级 转动惯量