On the brillouin-zone integrations in second-order many-body perturbation calculations for extended systems of one-dimensional periodicity

The validity and accuracy of various ways of drastically reducing the number of k-points in the Brillouin zone integrations occurring in second-order many- body perturbation calculations of one-dimensional solids has been investigated. The most promising approximation can recover correlation energies of polyethylene and polyacetylene within 1% of converged values at less than a tenth of usual computational cost. The quasi-particle energy bands have also been reproduced quantitatively with the same approximation.