Description#
gmx rotacf calculates the rotational correlation function
for molecules. Atom triplets (i,j,k) must be given in the index
file, defining two vectors ij and jk. The rotational ACF
is calculated as the autocorrelation function of the vector
n = ij x jk, i.e. the cross product of the two vectors.
Since three atoms span a plane, the order of the three atoms
does not matter. Optionally, by invoking the -d switch, you can
calculate the rotational correlation function for linear molecules
by specifying atom pairs (i,j) in the index file.
EXAMPLES
gmx rotacf -P 1 -nparm 2 -fft -n index -o rotacf-x-P1
-fa expfit-x-P1 -beginfit 2.5 -endfit 20.0
This will calculate the rotational correlation function using a first
order Legendre polynomial of the angle of a vector defined by the index
file. The correlation function will be fitted from 2.5 ps until 20.0 ps
to a two-parameter exponential.
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