Energies and diamagnetic coefficients of exciton in monolayer WSe2

This paper uses the socalled modulated perturbation method by combining the Rayleigh-Schrӧdinger perturbation theory with the Levi-Civita transformation and including a variational parameter. The advantage of the constructed method is demonstrated in calculating the exciton diamagnetic coefficient within the second order of approximation. The results are then compared with recent experimental ones.