Ab initio Monte Carlo shell model calculations for 7Li and 9Li low-lying spectra**Supported by Fundamental Research Funds for the Central Universities (JUSRP1035), National Natural Science Foundation of China (11305077)

Abstract

The low-lying spectra of 7Li and 9Li are investigated within an ab initio Monte Carlo Shell Model (MCSM) employing a realistic potential obtained via the Unitary Correlation Operator Method (UCOM). The MCSM calculations in a 4-major-shells model space for the binding energy and mass quadrupole moment of 7,9Li show good convergence when the MCSM dimension reaches 20. The excitation energy of the Jπ = 1/2− state for 7Li and the magnetic moments for 7,9Li ground states in the MCSM with a treatment of spurious center-of-mass motion are close to the experimental data. Correct level ordering of Jπ = 3/2− and 1/2− states for 7,9Li can be reproduced due to the inclusion of three-body correlations in the MCSM+UCOM. However, the excitation energy of Jπ = 1/2− state for 9Li is not reproduced in the MCSM mainly due to the lack of larger model space.