Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; China Inst Atom Energy, Beijing 102413, Peoples R China
; Natl Lab Heavy Ion Accelerator Lanzhou, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China
; Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China
The quasiparticle relativistic random phase approximation (QRRPA) is formulated based on the relativistic mean field ground state in the response function formalism. The pairing correlations are taken into account in the Bardeen-Cooper-Schrieffer approximation with a constant pairing gap. The numerical calculations are performed in the case of various isoscalar giant resonances of nucleus Sn-120 with parameter set NL3. The calculated results show that the QRRPA approach could satisfactorily reproduce the experimental data of the energies of low-lying states.