cmf_aa_ind_kernel: Indicator fields
In conmolfields: Continuous molecular fields

Indicator fields

1	cmf_aa_ind_kernel(field, atom1, atom2, alpha)

`field`
`atom1`
`atom2`
`alpha`

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
cmf_aa_ind_kernel <- function(field, atom1, atom2, alpha) {
  val <- 0.0
  if (field == atom1$syb && field == atom2$syb) {
    dist2 <- eucldist2(atom1, atom2)
    val <- exp(- alpha * dist2 / 4.0)
    val <- val * sqrt(pi^3 / alpha^3)
  }
  val
}