\(\renewcommand{\AA}{\text{Å}}\)

pair_style momb command

Accelerator Variants: momb/omp

Syntax

pair_style momb cutoff s6 d

  • cutoff = global cutoff (distance units)

  • s6 = global scaling factor of the exchange-correlation functional used (unitless)

  • d = damping scaling factor of Grimme’s method (unitless)

Examples

pair_style momb 12.0 0.75 20.0
pair_style hybrid/overlay eam/fs lj/charmm/coul/long 10.0 12.0 momb 12.0 0.75 20.0 morse 5.5

pair_coeff 1 2 momb 0.0 1.0 1.0 10.2847 2.361

Description

Style momb computes pairwise van der Waals (vdW) and short-range interactions using the Morse potential and (Grimme) method implemented in the Many-Body Metal-Organic (MOMB) force field described comprehensively in (Fichthorn) and (Zhou). Grimme’s method is widely used to correct for dispersion in density functional theory calculations.

\[\begin{split} E & = D_0 [\exp^{-2 \alpha (r-r_0)} - 2\exp^{-\alpha (r-r_0)}] - s_6 \frac{C_6}{r^6} f_{damp}(r,R_r) \\ f_{damp}(r,R_r) & = \frac{1}{1 + \exp^{-d(r/R_r - 1)}}\end{split}\]

For the momb pair style, the following coefficients must be defined for each pair of atoms types via the pair_coeff command as in the examples above, or in the data file or restart files read by the read_data as described below:

  • \(D_0\) (energy units)

  • \(\alpha\) (1/distance units)

  • \(r_0\) (distance units)

  • \(C_6\) (energy*distance^6 units)

  • \(R_r\) (distance units, typically sum of atomic vdW radii)

Styles with a gpu, intel, kk, omp, or opt suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed on the Accelerator packages page. The accelerated styles take the same arguments and should produce the same results, except for round-off and precision issues.

These accelerated styles are part of the GPU, INTEL, KOKKOS, OPENMP, and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the Build package page for more info.

You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the -suffix command-line switch when you invoke LAMMPS, or you can use the suffix command in your input script.

See the Accelerator packages page for more instructions on how to use the accelerated styles effectively.

Restrictions

This style is part of the EXTRA-PAIR package. It is only enabled if LAMMPS is built with that package. See the Build package page on for more info.

Default

none

(Grimme) Grimme, J Comput Chem, 27(15), 1787-1799 (2006).

(Fichthorn) Fichthorn, Balankura, Qi, CrystEngComm, 18(29), 5410-5417 (2016).

(Zhou) Zhou, Saidi, Fichthorn, J Phys Chem C, 118(6), 3366-3374 (2014).