Switch for SHAKE on Hydrogens

If TRUE, EGO uses the SHAKE algorithm to constrain the bond length of any hydrogen atom to its partner atom. This allows the use of longer integration time steps, usually 1fs to 2fs. For details see [40,26]. Note: Only the bond length, and not the angle, is constrained by SHAKE in EGO.

The utility program xpl2lis creates the file shake.lis which contains a list of all hydrogens and the respective heavy atoms to which they are bonded. EGO uses this list and shakes all hydrogens if this switch is set to TRUE. If, however, one does not like to shake all hydrogen atoms one can choose one of the following ways: The first way is to patch the shake.lis file, that is, one has to delete all hydrogen-heavy-atom list entries, to correct the total number of shaked atoms and to set the switch to TRUE in the control file. The other possibility is to use the keyword SHAKEOFF in the free format section (see Section 4.34.3).