# Vanderwaal's energy and energy minimisation

Hi,

I’m trying to solve a simple 2D elasticity problem using peridynamics, specifically the peri/pmb pair.

I would like to minimise the force 2-norm but the minimisation command seems to get stuck in a local energy minimum with some residual force. The minimise command I’m using is:

minimize 0 1e-6 1000 1000

This leaves a force residual (2-norm) of 0.8 in micro units.

One of the potential reasons is that I have huge evdwl in my system which I do not need. Is there a way to zero that out for the minimisation? Additionally when I use the minimise command multiple times one after the other the force residual can go as low as 0.007. Why is the first minimum different from the others?

Is there also a way to completely ignore the energy during minimisation and work only with forces?

Any help would be much appreciated.

Thank you,

Hi,

I’m trying to solve a simple 2D elasticity problem using peridynamics, specifically the peri/pmb pair.

I would like to minimise the force 2-norm but the minimisation command seems to get stuck in a local energy minimum with some residual force. The minimise command I’m using is:

minimize 0 1e-6 1000 1000

This leaves a force residual (2-norm) of 0.8 in micro units.

One of the potential reasons is that I have huge evdwl in my system which I do not need. Is there a way to zero that out for the minimisation? Additionally when I use the minimise command multiple times one after the other the force residual can go as low as 0.007. Why is the first minimum different from the others?

wouldn't a huge potential energy be an indication that there is