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Study on spectroscopic parameters and molecular constants of HCl(X1∑+) molecule by using multireference configuration interaction approach
Zhang Xiao-Niu(张小妞), Shi De-Heng(施德恒), Zhang Jin-Ping(张金平), Zhu Zun-Lüe(朱遵略), and Sun Jin-Feng(孙金锋)
Chin. Phys. B, 2010, 19 (5):
053401.
DOI: 10.1088/1674-1056/19/5/053401
Equilibrium internuclear separations, harmonic frequencies and potential energy curves (PECs) of HCl($X^{1}\Sigma ^{ + })$ molecule are investigated by using the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with a series of correlation-consistent basis sets in the valence range. The PECs are all fitted to the Murrell--Sorbie function, and they are used to accurately derive the spectroscopic parameters ($D_{\rm e}$, $D_{0}$, $\omega_{\rm e}\chi_{\rm e}$, $\alpha_{\rm e}$ and $B_{\rm e})$. Compared with the available measurements, the PEC obtained at the basis set, aug-cc-pV5Z, is selected to investigate the vibrational manifolds. The constants $D_{0}$, $D_{\rm e}$, $R_{\rm e}$, $\omega_{\rm e}$, $\omega_{\rm e}\chi_{\rm e}$, $\alpha_{\rm e}$ and $B_{\rm e}$ at this basis set are 4.4006 eV, 4.5845 eV, 0.12757 nm, 2993.33 cm$^{ - 1}$, 52.6273 cm$^{ - 1}$, 0.2981 cm$^{ - 1}$ and 10.5841 cm$^{ - 1}$, respectively, which almost perfectly conform to the available experimental results. With the potential determined at the MRCI/aug-cc-pV5Z level of theory, by numerically solving the radial Schr?dinger equation of nuclear motion in the adiabatic approximation, a total of 21 vibrational levels are predicted. Complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reproduced, which are in excellent agreement with the available Rydberg--Klein--Rees data. Most of these theoretical vibrational manifolds are reported for the first time to the best of our knowledge.
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