MP2 ground state calculation - Tutorial

This tutorial introduces how to calculate the ground state energy using second order Møller-Plesset perturbation theory (MP2) with VASP. Currently there are three implementations available:

• MP2: this was the first implementation in VASP and is very efficient for small systems, i.e. systems with less than ~40 valence electrons per unit cell or unit cells smaller than ~200 ų. The system size scaling of this algorithm is N⁵.
• LTMP2: the Laplace transformed MP2 algorithm has a lower scaling (N⁴) than the previous MP2 algorithm and is therefore efficient for large systems with unit cells larger than ~200 ų and more than ~40 valence electrons.
• stochastic MP2: faster calculations at the price of statistical noise can be achieved with the stochastic MP2 algorithm. It is an optimal choice for very large systems where only relative errors per valence electron (say 1 meV per valence electron) are relevant. Keeping the absolute error fixed, the algorithm exhibits a cubic scaling with the system size, N³, whereas for a fixed relative errror, a linear scaling, N¹, can be achieved. Note that there is no k-point sampling and no spin polarization implemented for this algorithm.

At first, one should select the best algorithm according to the considered system size. In the following, a step by step instruction is presented.

1. bandgap of Si in GW
2. bandstructure of Si in GW (VASP2WANNIER90)
3. bandstructure of SrVO3 in GW