The isomorphous Hendrickson-Lattman coefficient Ciso for this
reflection for this derivative.
-Fpobs2 * [sin(alphahcalc)2
- cos(alphahcalc)2]
Ciso = ------------------------------------
E2
E = (Fphobs - Fpobs - Fhcalc)2
for centric reflections
= [(Fphobs - Fpobs) * 21/2 - Fhcalc]2
for acentric reflections
Fpobs = the observed structure factor amplitude of the
native
Fphobs = the observed structure factor amplitude of the
derivative
Fhcalc = the calculated structure factor amplitude
from the heavy atom model
alphahcalc = the phase calculated from the heavy atom model