科研之友
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摘要
The potential energy curves (PECs) of the X-2 Sigma(+), A(2)Pi, B-2 Sigma(+), a(4)Sigma(+), 1(4)Pi, 1(4)Delta, 1(4)Sigma(-) and 2(2)Pi electronic states of the SiO+ cation are calculated using an ab initio quantum chemical method. The PEC calculations have been made for internuclear separations from 0.06 to 1.24 nm using the complete active space self-consistent field method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in combination with a correlation-consistent aug-cc-pV6Z basis set. To improve the quality of the PECs, core-valence correlation and relativistic corrections are included. The relativistic correction calculations are performed using the third-order Douglas-Kroll Hamiltonian approximation. The core-valence correlation corrections are included using a cc-pCVQZ basis set. The relativistic corrections are calculated at the level of the cc-pVQZ basis set. In order to obtain more reliable results, the PECs obtained by the MRCI calculations are also corrected for size-extensivity errors by means of the Davidson modification (MRCI + Q). The spectroscopic parameters are determined by fitting the vibrational levels, which are calculated by solving the ro-vibrational Schrodinger equation with these PECs. The spectroscopic results have been compared in detail with those reported in the literature. Excellent agreement has been found between the present results and the experimental ones. Using the Breit-Pauli operator, the spin-orbit coupling effect is included in the calculations of the Pi and Delta electronic states. Four Omega components of the 1(4)Delta, three Omega components of the 1(4)Pi and two Omega components of the A(2)Pi and 2(2)Pi electronic states have been studied. The complete vibrational states are determined for each electronic state. The vibrational level, inertial rotation and centrifugal distortion constants are calculated for each vibrational state of each electronic state. And those of the first 20 vibrational states of the X-2 Sigma(+), A(2)Pi and 2(2)Pi electronic states are reported for the non-rotating SiO+ cation. Comparison with the experimental data demonstrates that the present results are accurate.
