MacroModel Reference Manual - ISP

Chapter 4: Operation CodesIf the MC/SD simulation is unstable and fails, consider turning off long-range constant derivatives,by setting EXNB arg1 to 1, and increasing the non-bonded cutoffs to a large number, suchas 100 Å.arg1Monte Carlo frequencyNumber of molecular or stochastic dynamics steps for every Monte Carlo step inmixed mode MDMC simulations. The result of a block of arg2 Monte Carlo steps isone or more translations or rotations of coordinates and velocities. Any resultingstructure passing the Metropolis test is used for subsequent molecular dynamics orstochastic dynamics simulation and accordingly modifies the trajectory.0 Default value of arg1 is 1 for pure MDMC and 10 if importance sampling (IMPS) isbeing done.0 This argument may be varied to achieve the desired 100:1 ratio of stochastic dynamicssteps to conformational interconversions when IMPS is used.arg2Number of internal coordinates varied at each MC stepEach pair of atoms in a TORS command corresponds to one internal coordinatedegree of freedom. Each molecule moved by a MOLS command generates one (ifonly translation or only rotation being done) or two (if both translation and rotationlimits given) internal coordinate degrees of freedom.This argument is overridden by args 1 and 2 of the MCNV command. In addition,MCSD may dynamically override any user specification by using a built-in dynamicmethod of specifying limits on degrees of freedom varied. The adaptive mechanismmay, however, be turned off by specifying DEBG 103.0 Default: 1.>0 Number of internal coordinates to be varied at each step.