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What does "1-4 (#,#) interaction not within cut-off" mean? |
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Saturday, 10 September 2005 |
Some of your atoms have moved so two atoms separated by three bonds are separated by more than the cutoff distance. This is BAD. Most important: do not increase your cut-off! This error actually indicates that the atoms have very large velocities, which usually means that (part of) your molecule(s) is (are) exploding. If you are using LINCS for constraints, you probably also already got a number of LINCS warnings. When using SHAKE this will give rise to a SHAKE error, which halts your simulation before the "1-4 not within cutoff" error can appear.
There can be a number of reasons for the large velocities in your system. If it happens at the beginning of the simulation, your system might be not equilibrated well enough (e.g. it contains some bad contacts). Try a(nother) round of energy minimization to fix this. Otherwise you might have a very high temperature, and/or a too large timestep. Experiment with these parameters till the error stops occurring. If this doesn't help, check your topology!
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