              The isomorphous Hendrickson-Lattman coefficient A~iso~ for this\
               reflection for this derivative.\
\
                         -2.0 * (Fp~obs~^2^ + Fh~calc~^2^ - Fph~obs~^2^)\
                              *  Fp~obs~ * cos(alphah~calc~)\
               A~iso~ =  -----------------------------------------------\
                                              E^2^\
\
               E            = (Fph~obs~ - Fp~obs~ - Fh~calc~)^2^\
                              for centric reflections\
                            = [(Fph~obs~ - Fp~obs~) * 2^1/2^ - Fh~calc~]^2^\
                              for acentric reflections\
\
               Fp~obs~      = the observed structure factor amplitude of the\
                              native\
               Fph~obs~     = the observed structure factor amplitude of the\
                              derivative\
               Fh~calc~     = the calculated structure factor amplitude\
                              from the heavy atom model\
               alphah~calc~ = the calculated phase from the heavy atom model