COMPUTATION OF DIVERGING SUMS BASED ON A FINITE NUMBER OF TERMS

We propose a numerical method that permits us to compute the sum of a diverging series from only the first N terms by generalizing the traditional Borel technique. The method is rather robust and can be used to recover the ground state energy from the diverging perturbation theory for quantum field theoretical systems that are spatially constrained. Surprisingly, even the corresponding eigenvectors can be generated despite the intrinsic non-perturbative nature of bound state problems. [1-3] This work has been supported by the NSF, NSFC and Research Corporation. [1] C. Lisowski, S. Norris, R. Pelphrey, E. Stefanovich, Q. Su, R. Grobe, Ann. Phys. 373, 456 (2016). [2] Q.Z. Lv, S. Norris, R. Pelphrey, Q. Su, R. Grobe, Comp. Phys. Comm. 219, 1 (2017). [3] Q.Z. Lv, S. Dong, C. Lisowski, R. Pelphrey, Y.T. Li, Q. Su and R. Grobe, Phys. Rev. A 97, 053416 (2018)