LTMP2 - Tutorial

(UNDER CONSTRUCTION)

On this page, we explain how to perform a calculation using the LTMP2^[1] 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 ^[1] for details),

${\displaystyle \frac{1}{\varepsilon_i + \varepsilon_j - \varepsilon_a -\varepsilon_b} = - \int_0^\infty \textrm e^{-(\varepsilon_i + \varepsilon_j - \varepsilon_a -\varepsilon_b)\tau} \; \textrm d \tau \;. }$ .

Parallelization

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

References

↑ ^a ^b T. Schäfer, B. Ramberger, and G. Kresse, J. Chem. Phys. 146, 104101 (2017).

[schaefer2017-1] T. Schäfer, B. Ramberger, and G. Kresse, J. Chem. Phys. 146, 104101 (2017).

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