New implementation for GW Self-Energy evaluation

A new scheme for GW self-energy evaluation has been developed in YAMBO:

In this work, the multipole approximation (MPA) and the W-av methods have been integrated showing an improvement both in term of accuracy and speed-up of the calculation: the MPA accurately approximates full-frequency response functions using a minimal number of poles, while W-av enhances convergence concerning k-point sampling in 2D materials.

The method has been applied to free-standing graphene, a paradigmatic case. The results demonstrate outstanding agreement between the calculated quasiparticle band structure and experimental data obtained from angle-resolved photoemission spectroscopy. Moreover, the computational efficiency of MPA and W-av enables the investigation of the logarithmic renormalization of the Dirac cone.