Accurate<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>G</mml:mi><mml:mi>W</mml:mi></mml:mrow></mml:math>self-energies in a plane-wave basis using only a few empty states: Towards large systems

Abstract

The $GW$ approximation to the electronic self-energy yields band structures in excellent agreement with experimental data. Unfortunately, this type of calculation is extremely cumbersome even for present-day computers. The huge number of empty states required both in the calculation of the polarizability and of the self-energy is a major bottleneck in $GW$ calculations. We propose an almost costless scheme, which allows us to divide the number of empty states by about a factor of 5 to reach the same accuracy. The computational cost and the memory requirements are decreased by the same amount, accelerating all calculations from small primitive cells to large supercells.