[gmx-users] Maximun time-step recommended in the grompp part for each system

[Mario Fernández Pendás]

Some extra information about this topic:

We are exicitely interested in NOT using any kind of constraints. As you
may assume, the purpose of this study is purely theoretical.

Thank you very much.

Best regards,
Mario
El 11/12/2014 18:20, "Mario Fernández Pendás" <mariofp77 at gmail.com>
escribió:

> Dear all,
>
> Taking look at the check_bonds_timestep() function in src/kernel/grompp.c
> used for checking the time-step used for the integration of the equations
> of motion a few questions come to me:
>
> - In the comments of the function it is said that "The stability limit of
> leap-frog or velocity verlet is 4.44 steps per oscillational period". Does
> anyone know how this exact number is obtained?
>
> - I see that, inside of the function, there are two "limits": 5 and 10.
> They are used for establishing a relation between the estimated oscillation
> period of the bond between two atoms of the system in use and the time-step
> used for integrating the equations of motion and giving a warning message
> in case of using a non suitable time-step. I assume, looking at the
> literature, that this limits are taking from the following paper by Mazur:
> http://www.sciencedirect.com/science/article/pii/S0021999197957405
> Am I right?
>
> I have also found an issue in redmine for the function
> check_bonds_timestep() reporting that it only reports the first suspicious
> bond. I think this does not affect my questions.
>
> Thank you very much.
>
> Best regards,
> Mario
>