Lennard-Jones potential¶

The Lennard-Jones potential has the following functional form

$E = \sum_{ij} V(r_{ij})$

where

$V(r) = 4 \varepsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^{6} \right].$

Here, $$\varepsilon$$ and $$\sigma$$ are the two potential parameters that, respectively, define energy and length scale. The potential is truncated beyond a certain cutoff.

The following code snippet, to be inserted in the <potentials> block of the input file illustrates the definition of this potential type in the input file.

<lennard-jones id="Lennard-Jones" species-a="*" species-b="*">
<sigma>2.5</sigma>
<epsilon>0.5</epsilon>
<cutoff>10.0</cutoff>
<fit-dof>
<sigma />
<epsilon />
</fit-dof>
</lennard-jones>


Elements and attributes

• <sigma>: The initial value for the $$\sigma$$ parameter.
• <epsilon>: The initial value for the $$\varepsilon$$ parameter.
• <cutoff>: The cutoff radius.