TY - JOUR T1 - Avoided crossings between bound states of ultracold Cesium dimers JF - Physical Review A Y1 - 2008 A1 - Jeremy M. Hutson A1 - Eite Tiesinga A1 - Paul S. Julienne AB - We present an efficient new computational method for calculating the binding energies of the bound states of ultracold alkali-metal dimers in the presence of magnetic fields. The method is based on propagation of coupled differential equations and does not use a basis set for the interatomic distance coordinate. It is much more efficient than the previous method based on a radial basis set and allows many more spin channels to be included. This is particularly important in the vicinity of avoided crossings between bound states. We characterize a number of different avoided crossings in Cs_2 and compare our converged calculations with experimental results. Small but significant discrepancies are observed in both crossing strengths and level positions, especially for levels with l symmetry (rotational angular momentum L=8). The discrepancies should allow the development of improved potential models in the future. VL - 78 UR - http://arxiv.org/abs/0806.2583v1 CP - 5 J1 - Phys. Rev. A U5 - 10.1103/PhysRevA.78.052703 ER -