R.O. Gould, N. Moulden and P. Taylor, University of Edinburgh Version of September, 1988.
General Principle of operation:
An initial set of atomic
coordinates is read in from the previously prepared file
IDEAL.INS, and stored in
orthogonal Angstrom form. As each
subsequent set is read in, atom names common to it and the first set are
identified, and providing that at least three such atoms are found, an
attempt is made to superimpose the two sets. The initial fit is made
by:
The initial fit is then refined by iterative least squares, rotating the second set about the x-, y- and z-axes to minimise the sum of the squares of the deviations of equivalent atoms from one another until convergence (a change in the r.m.s. deviation of less than 0.1% of its previous value) occurs.