pair_style momb command

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{aligned} E & = D_{0} [\exp^{- 2 α (r - r_{0})} - 2 \exp^{- α (r - r_{0})}] - s_{6} \frac{C_{6}}{r^{6}} f_{d a m p} (r, R_{r}) \\ f_{d a m p} (r, R_{r}) & = \frac{1}{1 + \exp^{- d (r / R_{r} - 1)}} \end{aligned}

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)
$α$ (1/distance units)
$r_{0}$ (distance units)
$C_{6}$ (energy*distance^6 units)
$R_{r}$ (distance units, typically sum of atomic vdW radii)

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).