LTMP2 - Tutorial

(UNDER CONSTRUCTION)

On this page, we explain how to perform a calculation using the LTMP2 algorithm. Make sure you successfully completed the preparation steps Hartree-Fock ground state and Hartree-Fock virtuals.

The INCAR file

The LTMP2 calculation can simply be performed using the following INCAR file

ALGO = ACFDTRK 
LMP2LT = .TRUE.
NOMEGA = # number of tau points (see below)
NBANDS = # same valule as in the Hartree-Fock unoccupieds step ( = number of plane-waves)
ENCUT = # same value as in the Hartree-Fock step
LORBITALREAL = .TRUE.
PRECFOCK = Fast

Make sure that VASP reads the WAVECAR file from the Hartree-Fock virtuals step.

NOMEGA flag

The number of $\tau$-points is set with the NOMEGA flag. This is necessary to calculate the Laplace transformed energy denominator (see Ref for details),

${\frac {1}{\varepsilon _{i}+\varepsilon _{j}-\varepsilon _{a}-\varepsilon _{b}}}=-\int _{0}^{\infty }{\textrm {e}}^{-(\varepsilon _{i}+\varepsilon _{j}-\varepsilon _{a}-\varepsilon _{b})\tau }\;{\textrm {d}}\tau \;.$.

Parallelization

The LTMP2 algorithm is a high-performance code and can easily be used on many CPUs. Both OpenMP and MPI is supported.