We carry out calculations on the van der Waals trimer ' Li4He2 using the mapping method within the frame of hyperspherical coordinates, which allows us to give accurate binding energies and wave functions for both the ground and excited state of the system. When the realistic two-body potentials are adopted, the system presents an excited state which shows Efimov character. We study the range of the interaction strength in which the excited state could exist and find that the state persists within the experiment error band for binding energy of LiHe molecule. We also study the three-body parameter (3BP) of 7Li4He2 system and its relationship with the background scattering length a HeHe-Our calculations demonstrate that the 3BP of 7Li4He2 system is dependent on the value of the scattering length «HeHe> independent of the short-range details of the He-He interaction. The results confirm the prediction of Wang etal. [Phys. Rev. Lett. 109, 243201 (2012)] that the 3BPfor a heteronuclear atomic system is universally determined from the van der

The three-body parameter (3BP) a (1) − is crucial for understanding Efimov physics, and a universal 3BP has been shown in experiments and theory in ultracold homonuclear gases. The 3BP of heteronuclear systems has been predicted to possess much richer properties than its homonuclear counterparts due to the larger parameter space. In this work, we investigate the universal properties of a (1) − for heavy-heavy-light (HHL) systems with a negative intraspecies scattering length a HH . We find that a (1) − follows a universal behavior determined by the van der Waals (vdW) interaction and the mass ratio. A linear fit of a (1) − for large a HH leads to a simple formula, which gives the general dependence of a (1) − on the mass ratio and the vdW length r vdW,HL . In a special case, when the two heavy atoms are in resonance, a (1) − is approximately constant: a (1) − = −(6.3 ± 0.6) r vdW,HL . * huilihan@wipm.ac.cn 1 arXiv:1903.09565v3 [cond-mat.quant-gas]