Collision of cold CaF molecules: Towards evaporative cooling**Project supported by the National Natural Science Foundation of China (Grant Nos. 11604164 and U1810129), the Fund for Shanxi “1331 Project” Key Innovation Research Team, China (Grant No. 1331KIRT), and Excellent Youth Academic Leader in Higher Education of Shanxi Province, China (2018).

Abstract

Long range intermolecular interaction potential surface of CaF (2Σ+) was simulated by employing the MOLPRO program and using the RCCSD(T)/def2-TZVP theory. The predicted data were further fitted to obtain the collision cross-section. The elastic collision cross-section of CaF at the temperature around 2 mK is as high as 6.5×10−9 cm2 and the collision rate is over 4.1×106 Hz. Additionally, we found that an orientation electric field will simplify the intermolecular interaction potential function from quaternary into ternary and the collision cross-section will be raised by about three orders. All-optical evaporative cooling of cold CaF is discussed in the conclusion.