Abstract: Potential energy curves (PEC) of ground X²Π and A²Σ⁺ states of SiCl radical are calculated with internally contracted multireference configuration interaction approach in combination with Dunning's correlation-consistent basis sets. Reference energy and correlation energy are extrapolated to complete basis set limit. Scalar relativistic and core-valence correlation corrections are calculated. Spectroscopic parameters of X²Π and A²Σ⁺ states are obtained. With Breit-Pauli operator, PECs of X²Π_1/2 and X²Π_3/2 states are computed. Spectroscopic parameters of two Ω states are determined. Vibration manifolds are evaluated for two Λ-S and two Ω states of non-rotation SiCl radical by numerically solving radical Schrödinger equation of nuclear motion. For each vibrational state, vibrational levels and inertial rotation constants, spin-orbital coupling constants of X²Π state are determined.

Key words: potential energy curve, spectroscopic parameter, extrapolation of energy, spin-orbital coupling