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1.
Multireference configuration interaction potential curve and analytical potential energy function of the ground and low-lying excited states of CdSe
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The potential energy curves (PECs) of the ground state ($^{3}\Pi )$
and three low-lying excited states ($^{1}\Sigma $, $^{3}\Sigma $,$^{
1}\Pi )$ of CdSe dimer have been studied by employing
quasirelativistic effective core potentials on the basis of the
complete active space self-consistent field method followed by
multireference configuration interaction calculation. The four PECs
are fitted to analytical potential energy functions using the
Murrel--Sorbie potential function. Based on the PECs, the vibrational
levels of the four states are determined by solving the
Schr\"{o}dinger equation of nuclear motion, and corresponding
spectroscopic constants are accurately calculated. The equilibrium
positions as well as the spectroscopic constants and the vibrational
levels are reported. By our analysis, the $^{3}\Pi $ state, of which
the dissociation asymptote is Cd($^{1}$S) + Se($^{3}$P), is
identified as a ground state of CdSe dimer, and the corresponding
dissociation energy is estimated to be 0.39\,eV. However, the first
excited state is only 1132.49\,cm$^{ - 1}$ above the ground state and
the $^{3}\Sigma $ state is the highest in the four calculated states. 相似文献
2.
采用包含Davidson修正的多参考组态相互作用(MRCI+Q)方法结合6-311++G(3df,3pd)基组计算了LiC分子基态(X4Σ-)以及五个低电子激发态(a2Π,b2Δ,c2Σ-,d2Σ+,A4Π)的势能曲线.将得到的势能曲线拟合到Murrell-Sorbie解析势能函数形式,确定了对应态的平衡结构Re、谐振频率ωe和离解能De等光谱数据,计算值与仅有的几个其他结果进行了比较.通过求解核运动的薛定谔方程首次报道了LiC分子几个低电子态在J=0下的振动能级、转动惯量和六个离心畸变常数(Dν,Hν,Lν,Mν,Nν和Oν). 相似文献
3.
Xiaomei Zhang Xiaoting Liu Guiying Liang Dandan Shi Rui Li Xueshen Liu 《Molecular physics》2013,111(21):3312-3324
High-level ab initio calculations have been performed on the PBr radical by using multi-reference configuration interaction method plus Davidson correction (+Q) with correlation-consistent quadruple-ζ quality basis set. The potential energy curves (PECs) of the 22 Λ–S states of PBr have been obtained, most of which are reported for the first time. From the PECs of the bound states, the spectroscopic constants have been determined, in good agreement with the experimental results where available. Due to the large state density, there exhibits complicated interactions in the electronic excited states of PBr. The possible interactions by the spin–orbit coupling (SOC) effect have been discussed based on the evaluated R-dependent spin–orbit matrix elements. The 51 Ω states, generating from the 22 Λ–S states after taking SOC into account, have been computed. The Λ–S component analysis of the wavefunctions for the Ω states indicates the strong interaction of the Λ–S states especially at the avoided crossing points and near the dissociation limits. Finally, the transition dipole moments of several transitions arising from upper Ω states to the X10+ and X21 states and the corresponding radiative lifetimes have been studied. Our calculation results provide new information that should be valuable for further experimental studies on the electronic excited states of the PBr radical. 相似文献
4.
Multireference calculations on low-lying states and the X~3 Π_u -~3 Π_g absorption spectra of indium dimers
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Multireference configuration interaction calculations are carried out on 11 Λ-S low-lying electronic states of indium dimers. The states are investigated with spin-orbit pseudopotentials via the state-interacting method, and characterized by fitted spectroscopic constants based on computed potential energy curves. The vibrational structures of the double-potential well 0+g (I) ( 3 Σ g ) state are also analyzed. The experimentally observed absorption spectrum centred at ~ 13000cm-1 is simulated and assigned to X 3 Πu (v=0)-3Πg transition according to the present ab initio calculations on transition energies and dipole moment functions. 相似文献
5.
本文以aug-cc-pv5Z为基组, 采用考虑Davidson修正的多参考组态相互作用方法(MRCI+Q)得到了GeS分子基态(X1Σ+)和5个低激发态(11Σ, 11Δ, A1Π, 15Σ+, 25Σ+)的势能曲线. 计算结果表明: 25Σ+态为排斥态, 其余5个态为束缚态; 6个态有着共同的离解通道, 离解极限均为Ge(3P)+S(3P). 利用计算得到的势能曲线得了X1Σ+, 11Σ-, 11Δ, A1Π和15Σ+态的垂直跃迁能Te, 平衡键长Re, 离解能De, 谐振频率ωe, 非谐性常数ωexe及平衡位置的电偶极矩. X1Σ+态的Re 为2.034 Å, De 为5.728 eV, ωe为571.73 cm-1, ωexe为1.6816 cm-1, 平衡位置的电偶极矩为1.9593 Debye. 激发态11Σ, 11Δ, A1Π, 15Σ+的Te 依次为25904.81, 26209.22, 32601.19, 43770.26 cm-1; Re依次为2.313, 2.322, 2.188, 2.8790 Å; De依次为2.524, 2.487, 1.694, 0.3036 eV, ωe依次为358.90, 353.08, 376.32, 134.96 cm-1; ωexe依次为1.2421, 1.2151, 1.6608, 1.9095 cm-1; 平衡位置的电偶极矩依次为1.3178, 1.4719, 1.5917, -1.9785 Debye. 通过求解核运动的薛定谔方程得到了J=0时X1Σ+, 11Σ-, 11Δ, A1Π和15Σ+态前30个振动态的振动能级Gv和分子常数Bv, 得到的结果和已有的实验值及其他理论值符合较好. 相似文献
6.
Multireference configuration interaction study on spectroscopic properties of low-lying electronic states of As2 molecule
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The potential energy curves (PECs) of four electronic states (X1Σ+g , e3△u , a 3 Σ-u , and d 3Πg ) of an As 2 molecule are investigated employing the complete active space self-consistent field (CASSCF) method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the correlation-consistent aug-cc-pV5Z basis set. The effect on PECs by the relativistic correction is taken into account. The way to consider the relativistic correction is to employ the second-order Douglas-Kroll Hamiltonian approximation. The correction is made at the level of a cc-pV5Z basis set. The PECs of the electronic states involved are extrapolated to the complete basis set limit. With the PECs, the spectroscopic parameters (Te , Re , ωe , ωexe , ωeye , αe , βe , γe , and Be ) of these electronic states are determined and compared in detail with those reported in the literature. Excellent agreement is found between the present results and the experimental data. The first 40 vibrational states are studied for each electronic state when the rotational quantum number J equals zero. In addition, the vibrational levels, inertial rotation and centrifugal distortion constants of d 3Πg electronic state are reported which are in excellent agreement with the available measurements. Comparison with the experimental data shows that the present results are both reliable and accurate. 相似文献
7.
Yufeng Gao 《Molecular physics》2014,112(23):3015-3023
The ground and low-lying excited states of MgLi and MgLi+ molecules have been investigated. The potential energy curves and the permanent and transition dipole moments of the MgLi and MgLi+ molecules are determined making use of the multi-reference configuration interaction and valence full configuration interaction with large basis sets. The core–valence correlation and scalar relativistic correction are also taken into account with aug-cc-pCVQZ basis set and the third-order Douglas–Kroll Hamiltonian approximation, respectively. The transition dipole moments are used to evaluate the radiative lifetimes of the vibrational levels for the low-lying excited states of the MgLi and MgLi+ molecules. The derived spectroscopic constants of the ground and low-lying excited states are in good agreement with available experimental and theoretical works. 相似文献
8.
Based on a high level ab initio calculation which is carried out with the multireference configuration interaction method under the aug-cc-pVXZ (AVXZ) basis sets, X=T, Q, 5, the accurate potential energy curves (PECs) of the ground state ${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$ and the first excited state ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$ of Li2 are constructed. By fitting the ab initio potential energy points with the Murrell–Sorbie potential function, the analytic potential energy functions (APEFs) are obtained. The molecular bond length at the equilibrium (Re), the potential well depth (De), and the spectroscopic constants (Be, ωe, αe, and ωeχe) for the ${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$ state and the ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$ state are deduced from the APEFs. The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrödinger equation with the Fourier grid Hamiltonian method. All the spectroscopic constants and the vibrational levels agree well with the experimental results. The Franck–Condon factors (FCFs) corresponding to the transitions from the vibrational level (v′=0) of the ground state to the vibrational levels (v″=0–74) of the first excited state have been calculated. The FCF for the vibronic transition of ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$(v″=0) ←${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$(v′=0) is the strongest. These PECs and corresponding spectroscopic constants provide reliable theoretical references to both the spectroscopic and the molecular dynamic studies of the Li2 dimer. 相似文献
9.
CS molecule, which plays a key role in atmospheric and astrophysical circumstances, has drawn great attention for long time. Owing to its large state density, the detailed information of the electronic structure of CS is still lacking. In this work, the high-level MRCI+Q method is used to compute the potential energy curves, dipole moments and transition dipole moments of singlet and triplet states correlated with the lowest dissociation limit of CS, based on which high accurate vibration—rotation levels and spectroscopic constants of bound states are evaluated. The opacity of CS relevant to atmospheric circumstance is computed at a pressure of 100 atms for different temperatures. With the increase of temperature, band systems from different transitions mingle with each other, and band boundaries become blurred, which are originated from the increased population on vibrational excited states and electronic excited states at high temperature. 相似文献
10.
The potential energy curves (PECs) of four low-lying electronic states of the BO radical, including two 2Σ+ and two 2Π states, have been studied 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 in combination with the cc-pV5Z basis set for internuclear separations from 0.05 to 2.0 nm. The effect on the PECs by the relativistic correction has been taken into account. With these PECs, the spectroscopic parameters (Te, D0, De, Re, ωe, ωexe, αe and Be) of two main isotopologues (11B16O and 10B16O) have been determined. These parameters have been compared in detail with those of previous investigations reported in the literature, and excellent agreement has been found between the available data and the present results. By solving the radial Schrödinger equation of nuclear motion, 60 vibrational states for the 11B16O(X2Σ+), 60 for the 10B16O(X2Σ+), 66 for the 11B16O(A2Π) and 64 for the 10B16O(A2Π) are predicted for the non-rotating molecule. For each vibrational state of the 11B16O(X2Σ+), 10B16O(X2Σ+), 11B16O(A2Π) and 10B16O(A2Π), the vibrational level G(υ), inertial rotation constant Bυ and centrifugal distortion constant Dυ have been determined. Comparison with the available data shows that the present molecular constants are reliable and accurate. The ro-vibrational levels have been calculated for the X2Σ+ and A2Π states of two main species for future laboratory research. 相似文献
11.
The potential energy curves (PECs) are calculated for the 20 Λ-S states (X2Πg, A2Πu, B2Σ?g, a4Πu, b4Σ?g, b′4Πg, c4Σ?u, 12Σ+g, 12Σ+u, 12Σ?u, 14Σ+g, 14Σ+u, 14Δg, 14Δu, 16Σ+g, 16Σ+u, 16Πg, 16Πu, 24Πg and 24Πu) of O2+ cation and their corresponding 58 Ω states. Of these 20 Λ-S states, the 16Πu state is found to be repulsive. The 12Σ+g, 14Σ+u, c4Σ?u and 14Δu states are found to possess the double well. The b4Σ?g, 16Σ+g, 14Σ+u, a4Πu, A2Πu, 16Πg and 24Πg states are found to be inverted with the spin–orbit coupling effect included. The b′4Πg, 16Πg, 16Σ+g, 14Σ+u and 14Δu states, and the second well of the 12Σ+g state are found to be the weakly bound states. The b′4Πg state is found to possess one well with one barrier. The PECs are calculated by the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson correction in combination with the aug-cc-pV6Z basis set. The core–valence correlation and scalar relativistic corrections are included. The convergent behaviour of present calculations is discussed with respect to the basis set and theoretical level. The spin–orbit coupling effect is accounted for. The PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated, and compared with available measurements. It demonstrates that the spectroscopic parameters reported here can be expected to be reliably predicted ones. 相似文献
12.
The multi-reference configuration interaction (MRCI) electronic energy calculations have been carried out on the ground state (X1∑) as well as three low-lying excited states (3∑, 1∏, 3∏) of ZnCd dimer. Potential energy curves (PECs) are therefore generated and fitted to the analytical potential energy functions (APEFs) using the Murrel-Sorbie(MS) potential function. Based on the PECs, the vibrational levels of each state are determined by solving Schr(o)dinger equation of nuclear motion, and corresponding spectroscopic parameters are accurately calculated using the APEFs. The present values of spectroscopic parameters including equilibrium positions and dissociation energies areompared with other theoretical reports available at present. 相似文献
13.
基于相关一致极化4zeta(aug-cc-pVQZ)基组, 应用量子化学从头计算中高水平的多参考组态相互作用方法计算了BCl+ 两个离解极限B+(1Sg)+Cl(2Pu)和B (2Pu)+Cl+ (3Pg)的14个Λ-S态势能曲线. 在计算中考虑了Davidson修正(+Q)和标量相对论效应, 并首次在计算中考虑了BCl+ 的旋轨耦合效应, 获得了由能量最低的4个Λ-S态分裂出的7个Ω 态. 计算结果表明相同对称性的Ω 态的势能曲线存在着非常明显的避免交叉. 通过分析Λ-S态的电子结构, 得到了各态的电子跃迁特性, 并确认了电子态的多组态性质. 使用LEVEL程序通过求解径向的Schrödinger方程得到了束缚Λ-S 和Ω态的光谱参数De, Re, Te, ωe, ωeχe和Be. 通过和已有的Λ-S态X2∑+ 的实验数据进行对比发现, 本文所得的计算结果与实验结果非常一致. 而文中其他电子态的光谱参数均为首次报道.
关键词:
势能曲线
光谱参数
多参考组态相互作用方法
旋轨耦合 相似文献
14.
本文利用量子化学中的多参考组态相互作用方法(MRCI), 在aug-cc-pVQZ级别计算了在环境科学中具有重要作用的离子BP+. 得到了对应三个离解极限B+(1Sg)+P(4Su), B+(1Sg)+P(2Du)以及B+(1Sg)+P(2Pu)的6个Λ-S态势能曲线. 在计算中还考虑了Davidson修正(+Q)和标量相对论效应, 用以提高计算精度. 通过分析Λ-S态的电子结构, 确认了电子态的多组态特性. 计算中首次纳入了旋轨耦合效应, 获得了由BP+离子的6个Λ-S态分裂出的10个Ω 态的势能曲线. 计算得到的势能曲线表明相同对称性的Ω 态的势能曲线存在着明显的避免交叉. 在得到的Λ-S态和Ω 态的势能曲线的基础上, 运用LEVEL8.0程序通过求解核径向的Schrödinger 方程, 得到了相应的Λ-S态和Ω 态的光谱常数Te, Re, ωe, ωeχe, Be和De, 其中基态X4∑-的光谱常数与已有的理论值符合的非常好, 文中其他电子态的光谱常数均为首次报道.
关键词:
多参考组态相互作用方法(MRCI)
势能曲线
光谱常数
旋轨耦合效应 相似文献
15.
16.
BeC是一个具有丰富低激发电子态的分子,本文基于动态权重完全活性空间自冾场方法获得的参考波函数,采用多参考组态相互作用方法对BeC分子进行高精度的从头计算,获得了BeC分子X~3Σ~-,A~3Π,b~1Δ,c~1Π和d~1Σ~+共5个电子态的势能曲线.为了获得精确的光谱结果,在计算中考虑了标量相对论效应修正,并把相互作用能外推至完全基组极限.在此基础上获得了这些态的光谱常数和偶极距,以及一些允许跃迁的跃迁偶极距、弗兰克-康登因子和辐射寿命.最后,通过扩展的Rydberg函数拟合获得了基态势能曲线精确的解析表达式. 相似文献
17.
利用单双激发多参考组态相互作用方法获得了LiAl分子基态X1∑+及七个激发态a3∏, A1∏, b3∑+, c3∑+, B1∏, C1∑+, d3∏的势能曲线, 通过势能曲线得到各态的平衡核间距Re, 进而求得绝热激发能和垂直激发能.计算结果表明:c3∑+ 电子态是一个不稳定的排斥态, A1∏态是一个较弱的束缚态, 其余6个电子态均为束缚态; b3∑+与 c3∑+态之间存在预解离现象; 8个电子态分别解离到两个通道, 即Li(2S)+Al(2P0)与Li(2P0)+Al(2P0). 接着将势能曲线拟合到Murrel-Sorbie解析势能函数形式, 据此获得各态的光谱数据:基态X1∑+的平衡键长为0.2863 nm, 谐振频率为316 cm-1, 解离能De为1.03 eV, 激发态a3∏, A1∏, b3∑+, c3∑+, B1∏, C1∑+, d3∏的垂直激发能依次为0.27, 0.83, 1.18, 1.14, 1.62, 1.81, 2.00 eV; 解离能依次为1.03, 0.82, 0.26, 排斥态, 1.54, 1.10, 0.93 eV, 相应谐振频率 ωe为339, 237, 394, 排斥态, 429, 192, 178 cm-1. 通过求解核运动的薛定谔方程找到了J=0时 LiAl分子7个束缚电子态的振动能级和转动惯量.
关键词:
LiAl
光谱常数
势能曲线
振动能级 相似文献
18.
Ab initio MRCI+Q study on potential energy curves and spectroscopic parameters of low-lying electronic states of CS+
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Carbon monosulfide molecular ion (CS+), which plays an important role in various research fields, has long been attracting much interest. Because of the unstable and transient nature of CS+, its electronic states have not been well investigated. In this paper, the electronic states of CS+ are studied by employing the internally contracted multireference configuration interaction method, and taking into account relativistic effects (scalar plus spin–orbit coupling). The spin–orbit coupling effects are considered via the state-interacting method with the full Breit–Pauli Hamiltonian. The potential energy curves of 18 Λ–S states correlated with the two lowest dissociation limits of CS+ molecular ion are calculated, and those of 10 lowest Ω states generated from the 6 lowest Λ–S states are also worked out. The spectroscopic constants of the bound states are evaluated, and they are in good agreement with available experimental results and theoretical values. With the aid of analysis of Λ–S composition of Ω states at different bond lengths, the avoided crossing phenomena in the electronic states of CS+ are illuminated. Finally, the single ionization spectra of CS (X1Σ+) populating the CS+(X2Σ1/2+, A2Π3/2, A2Π1/2, and B2Σ1/2+) states are simulated. The vertical ionization potentials for X2Σ1/2+, A2Π3/2, A2Π1/2, and B2Σ1/2+ states are calculated to be 11.257, 12.787, 12.827, and 15.860 eV, respectively, which are accurate compared with previous experimental results, within an error margin of 0.08 eV~0.2 eV. 相似文献
19.
利用原子分子反应静力学推导出AsCl自由基的基态及激发态的理解极限. 采用完全活性空间自洽场和含Davidson 修正的内收缩多参考组态相互作用理论方法, 在aug-cc-pV5Z基组下对AsCl自由基进行结构优化计算及单点能扫描计算. 在AsCl自由基基态势能曲线的基础上, 通过Molcas程序拟合出了AsCl的光谱常数De, Re, ωe, ωeχe, Be 和αe. 通过求解双原子分子核运动的径向Schrödinger方程, 找到了J=0 时该分子基态存在的40个振动态. 针对每一振动态, 计算了其振动能级、转动惯量Bν和离心畸变常数Dν, 与现有的实验及其他理论相比较, 本文的光谱参数和分子常数结果更准确.
关键词:
AsCl
势能函数
光谱常数 相似文献
20.
This work computed the potential energy curves of 19 Λ-S states, which arose from the first five dissociation limits of BC+ cation, B+(1Sg) + C(3Pg), B+(1Sg) + C(1Dg), B+(1Sg) + C(1Sg), C+(2Pu) + B(2Pu), and B+(1Sg) + C(5Su). The calculations were done for internuclear separations from 0.08 to 1.07 nm. The potential energy curves of 36 Ω states yielded from these Λ-S states were also calculated. Core-valence correlation and scalar relativistic correction, basis set extrapolation as well as Davidson correction were accounted for. Of these Λ-S states, the c1Σ+, D3Π, 21Π, 23Σ+, 21Δ, 31Σ+, and 41Σ+ had double wells; the 33Π and 31Π states had three wells; the C3Σ? and D3Π states were inverted with the spin-orbit coupling effect included; and the second wells of c1Σ+, D3Π and 31Σ+ states, the second and the third wells of 33Π state as well as the third well of 31Π state were very weakly bound, which well depths were smaller than 400 cm?1. The spectroscopic parameters were determined for all the states. The vibrational properties were predicted only for some weakly bound states. The spin-orbit coupling effect on the spectroscopic parameters was evaluated. 相似文献