              The isomorphous Hendrickson-Lattman coefficient C~iso~ for this\
               reflection for this derivative.\
\
                         -Fp~obs~^2^ * [sin(alphah~calc~)^2^\
                                     -  cos(alphah~calc~)^2^]\
               C~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 phase calculated from the heavy atom model