Investigations on molecular structure and analytic potential energy function of the AsH(X3Σ-) and AsH2(C2v，X2B1) radicals

Abstract

The CCSD(T) theory in combination with the cc-pV5Z basis set is used to determine the equilibrium geometry，dissociation energy and vibrational frequencies of AsH2(C2v，X2B1) radical. By comparison，excellent agreement can be found between the present results and the experiments. The values obtained at present are of 01508 nm for the equilibrium bond length RAs-H，912231° for the bond angle ∠HAsH，28795 eV for the dissociation energy De(HAs-H) and 10133361 cm-1，22251347 cm-1 and 22337565 cm-1 for the vibrational frequencies ν1(a1)，ν2(a1) and ν3(a1)，respectively. The equilibrium geometry，harmonic frequency and potential energy curve of the AsH(X3Σ-) radical are calculated at the CCSD(T)/cc-pV5Z level of theory. The ab initio results are fitted to the Murrell-Sorbie function with the least-square method. The spectroscopic parameters are in excellent agreement with the experiments. The analytic potential energy function of the AsH2(C2v，X2B1) radical is derived by using the many-body expansion theory. This function correctly describes the configuration and dissociation energy of the AsH2(C2v，X2B1) radical. Two symmetrical saddle points have been found at (0160 nm，0296 nm) and (0296 nm，0160 nm)，respectively. And the barrier height is equal to 01512×4184 kJ/mol.