MacroModel Reference Manual - ISP

Chapter 4: Operation CodesCHIG — CHIrality checking (Global)This command identifies and saves the chirality of the atoms listed in the arguments, andrejects structures whose chirality has changed during the calculation. The chirality is storedonly for the first structure in the input file. All structures are subsequently checked against thechirality of the first. Used with MULT, MCSM, MCMM, LMCS, LMC2, and LOOP for files of identicalstructures differing only in conformation.Use as many CHIG commands as necessary to save all important chiralities.CHIG commands must come after the READ command in the .com file. With MCMM searching,chirality is checked after the Monte Carlo step and also after the following energy minimization.arg1Atom number of chiral center0 Automatically perceive chirality. See the AUTO opcode. arg2-4 are ignored.>0 Atom number.arg2-4Atom numbers of chiral centers>0 Atom number.arg8Chirality reporting1 Report chirality identification.COMP — structure atom COMParisonArg1-4 are atom numbers to be used for comparing a minimized structure with all previousunique minima found. COMP may be specified up to 50 times to allow up to 200 atoms to beused in the comparisons. If COMP is not specified, the program will not attempt to eliminateduplicate minima. Structures are considered the same unless the least squares superimpositionof the compared atoms finds one or more pairs of equivalent atoms separated by more than theseparation given by the CRMS command (default = 0.25 Å). It is not necessary to specify allatoms in a molecule for comparison, but a representative sampling from widely separatedpoints in the structure should be given in COMP commands.arg1First atom number for comparison0 Generate comparison atom list automatically based on arg7 values.arg2-4Additional atom numbers for comparison76MacroModel 9.7 Reference Manual