The influence of collision energy on magnetically tuned^(6)Li-^(6)Li Feshbach resonance

The effect of collision energy on the magnetically tuned^(6)Li-^(6)Li Feshbach resonance(FR)is investigated theoretically by using the coupled-channel(CC)method for the collision energy ranging from 1μK·kBto 100μK·kB.At the collision energy of 1μK·kB,the resonance positions calculated are 543.152 Gs(s wave,the unit 1 Gs=10^(-4)T),185.109 Gs(p wave|ml|=0),and 185.113 Gs(p wave|ml|=1),respectively.The p-wave FR near 185 Gs exibits a doublet structure of 4 mGs,associated with dipole-dipole interaction.With the increase of the collision energy,it is found that the splitting width remains the same(4 mGs),and that the resonance positions of s and p waves are shifted to higher magnetic fields with the increase of collision energy.The variations of the other quantities including the resonance width and the amplitude of the total scattering section are also discussed in detail.The thermally averaged elastic rate coefficients at T=10,15,20,25 K are calculated and compared.

Ab initio calculation of the ground and first excited states of the lithium dimer

Based on a high level ab initio calculation which is earned out with the multireference configuration interaction method under the aug-cc-pVXZ(AVXZ)basis sets,X=T,Q,5,the accurate potential energy curves(PECs)of the ground state X^(1)Σ_(g)^(+)and the first excited state A^(1)Σ_(u)^(+)of Li_(2)are constructed.By fitting the ab initio potential energy points with the MurrellSorbie potential function,the analytic potential energy functions(APEFs)are obtained.The molecular bond length at the equilibnum(R_(e)),the potential well depth(D_(e)),and the spectroscopic constants(B_(e),ω_(e),α_(e),andω_(e)χ_(e))for the X^(1)Σ_(g)^(+)state and the A^(1)Σ_(u)^(+)state are deduced from the APEFs.The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrodmger equation with the Founer gnd Hamiltonian method.All the spectroscopic constants and the vibrational levels agree well with the experimental results.The Franck-Condon factors(FCFs)corresponding to the transitions from the vibrational level(v’=0)of the ground state to the vibrational levels(v"=0-74)of the first excited state have been calculated.The FCF for the vibronic transition of A^(1)Σ_(u)^(+)(v"=0)←X^(1)Σ_(g)^(+)(v’=0)is the strongest.These PECs and corresponding spectroscopic constants provide reliable theoretical references to both the spectroscopic and the molecular dynamic studies of the Li_(2)dimer.