Theoretical calculations of nonlinear optical calculations of 2D materials G.B. Ventura, D.J. Passos, J.M. Viana Parente Lopes and J.M.B. Lopes dos Santos EPJ Web Conf., 233 (2020) 03001 Published online: 16 April 2020 DOI: 10.1051/epjconf/202023303001