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Morse potential

Potential form of the Morse potential is,

\[\begin{equation*} E_{ij}(R_{ij}) = D_{ij} \left\{ [\exp (\alpha_{ij} (R_{0,ij} -R_{ij}))-1]^2 -1\right\} \end{equation*}\]

The potential requires a parameter file in.params.Morse that has the following format.

#  isp, jsp, D_ij, alpha_ij, R0_ij
1    1    3.7    2.0    1.68
1    2    3.2    1.9    2.5
2    2    2.5    2.1    2.3

In the above case, there are three interactions between 1-1, 1-2 and 2-2. Each interaction has three parameters:

  • D_ij: depth of the potential curve (eV)
  • alpha_ij: related to the width of the potential well (Ang.^{-1}).
  • R0_ij: position of the potential minimum (Ang.)