Potential energy curves and UV absorption cross-sections of sulfur dimer

MRCI-F12+Q/aug-cc-pV(5+d)Z ab initio potential energy and transition dipole moment curves of three S2 electronic states: X^3\Sigma_g^-, B''^3\Pi_u (both x,y degeneracies), B^3\Sigma_u^-. In addition, absorption cross-sections are included for four isotopologues (32S32S, 33S32S, 34S32S, and 36S32S) at T=300K. Additional two absorption cross-sections are included for 32S32S at T=370K and 823K for comparison with experimental cross-sections produced by Stark et al., J. Chem. Phys. 148, 244302 (2018). The absorption cross-sections are in cm^2 and the wavelength is in nm. Potential energy curves are in Hartree and interatomic distance is in Aangstrom. For linelists, the filename convention is used as follows: discrete_[excited electronic state e]_[ground electronic v]_[ground electronic J].dat for all discrete transitions from the specific v,J state to e. Indices are 0: B''^3Pi_ux; 1: B''^3Pi_uy; 2: B^3sigma_u^- The linelist contents are displayed in two main columns: [Energy (Hartree), Cross-section (cm^2)] and for the B^3sigma_u^- state, i.e. discrete_2_i_j.dat files: [Energy (Hartree), Cross-section (cm^2), Gamma (cm^-1)] where Gamma is the pre-dissociation FWHM broadening factor for states with energy greater than the dissociation energy for B''^3Pi_u state. The factor Gamma is calculated according to the close-coupling method shown in van Dischoeck et al. (1984), https://doi.org/10.1063/1.447622. However, we are not certain with the complete accuracy of it, since we have not included spin-orbit coupling interactions, which is expected to have an effect on the pre-dissociation factor. continuum_[excited electronic state e]_[ground electronic v]_[ground electronic J].dat for evenly spaced continuum transitions from the specific v,J state to e. Indices are 0: B Pi_ux; 1: B Pi_uy; 2: B_sigma_u [Energy (Hartree), Cross-section (cm^2)] gnd_energies.dat for all ground state v, J levels [v, J, Energy (Hartree)] The attached python script total_csection.py can be used to reproduce the total absorption cross-sections from linelists for each isotopologue by renaming the linelist directory to 'results' and putting in the same working directory as the script. Invoking the script, e.g.: >>python3 total_csection.py --recalc --temp 300 --isos 32S 32S will produce the total absorption cross-section with Boltzmann distribution and Doppler broadening at 300 Kelvin for 32S32S molecule.本数据集包含采用MRCI-F12+Q/aug-cc-pV(5+d)Z级别从头算（ab initio）得到的三种S₂电子态的势能曲线与跃迁偶极矩曲线：基态X^3Σ_g^-、B''^3Π_u（包含x、y二重简并构型）以及B^3Σ_u^-。 此外，数据集还包含四种同位素分子（³²S³²S、³³S³²S、³⁴S³²S及³⁶S³²S）在T=300K下的吸收截面数据。额外针对³²S³²S分子，补充了T=370K与823K下的吸收截面，用于与Stark等人发表于《The Journal of Chemical Physics》148卷244302页（2018年）的实验截面进行对比。 吸收截面单位为cm²，波长单位为nm；势能曲线单位为哈特里（Hartree），原子间距离单位为埃（Å）。 关于线表（linelists）文件，命名规则如下： 1. 离散跃迁文件：格式为"discrete_[激发电子态e]_[基态振动量子数v]_[基态转动量子数J].dat"，对应从特定v、J能级跃迁至激发态e的离散跃迁数据。其索引规则为：0对应B''^3Π_ux，1对应B''^3Π_uy，2对应B^3Σ_u^-。 2. 离散跃迁文件的内容包含两大列：[能量（哈特里），截面（cm²）]；而针对B^3Σ_u^-态的离散跃迁文件（即"discrete_2_i_j.dat"），额外包含第三列：[能量（哈特里），截面（cm²），预解离半高全宽（FWHM）因子Γ（cm⁻¹）]。其中Γ为能量高于B''^3Π_u态解离能的态的预解离展宽因子，其计算依据van Dischoeck等人1984年提出的密耦合方法（DOI: 10.1063/1.447622）。需注意，由于未考虑自旋-轨道耦合相互作用，该预解离因子的准确性尚未完全确认，而自旋-轨道耦合预计会对预解离因子产生影响。 连续跃迁文件格式为"continuum_[激发电子态e]_[基态振动量子数v]_[基态转动量子数J].dat"，对应从特定v、J能级跃迁至激发态e的均匀间隔连续跃迁数据。其索引规则为：0对应B Π_ux，1对应B Π_uy，2对应B Σ_u^-，文件内容列为[能量（哈特里），截面（cm²）]。 "gnd_energies.dat"文件包含所有基态v、J能级的数据，格式为[v, J, 能量（哈特里）]。 附带的Python脚本"total_csection.py"可用于从线表中复现各同位素分子的总吸收截面：只需将线表目录重命名为"results"并放置于脚本的同级工作目录中，即可运行该脚本。例如执行命令：>>python3 total_csection.py --recalc --temp 300 --isos 32S 32S，即可生成³²S³²S分子在300K下考虑玻尔兹曼分布与多普勒展宽的总吸收截面。