MacroModel Reference Manual - ISP

Chapter 4: Operation CodesSPMC searches are conducted starting from a single input structure. However, if the necessaryREAD and MINI opcodes are placed within a BGIN/END loop, then a separate search is carriedout ion each input structure. This is called a serial search. AUTO may be used to set up singleSPMC searches and is required for serial SPMC searches.It is suggested that torsional memory (MCSS arg3) be activated when using SPMC to preventretracing of points in conformational space when starting from different starting geometries. Ifrings are being varied (i.e., RCA4 commands are being used), geometrical preoptimization(MCOP arg2) should also be activated.Use with MCNV arg1=1 and arg2=N−1, where N is the number of variable torsions plus thenumber of molecules being independently translated/rotated with MOLS commands.Details of the method are provided by Goodman and Still [37].The arguments are the same as for MCMM, except arg3:arg3Maximum resolution for torsional alterationsDefault: 24, implying angular resolution of 360˚ / 24 = 15˚.MCOP — Monte Carlo OPtionsThis command alters the data written to the .log file, and also the geometrical optimizationroutine. If MCOP is omitted, this is equivalent to setting arg1=250 and arg2=0.Note:arg1Despite its name, MCOP specifies parameters for use in low-mode (LMCS and LMC2)and LOOP calculations, as well as Monte Carlo searches. Arguments 4 and 5 onlyapply to LMCS and LMC2 jobs. Starting in MacroModel 6.5, these arguments have newmeanings and arguments 6 and 7, which pertained to the earlier LMCS methodology,have been eliminated.Number of steps between printout to log-file0 Print to log file every 250 Monte Carlo steps.1 Print to log file every step.narg2Print to log file every n steps.Geometrical preoptimization0 Off.1 On. Preoptimizes variable internal coordinates to improve ring closure distances.Recommended for SPMC of ring systems.MacroModel 9.7 Reference Manual 103