Re: [ESPResSo-users] zero angle (full angle)

[Ulf Schiller]

Hi,

On 16/04/15 14:44, Dudo wrote:
> Hi,
> 
> I'm trying to implement a zero angle potential with minima at 0 or 2*pi
> respectively.

How would you decide whether the angle is in [0,pi] or [pi,2*pi] ?

> For this I just added a phase shift into the former angle_harmonic.hpp
> potential:
> 
> cos_phi = scalar(vec21, vec31) / (vec21_magn * vec31_magn) -
> (3.141592653589793238462 / 2.000000000000000);

This does not seem to make sense. cos_phi should be in the range [-1,1].

> However, in my model I would need also flat angle and right angle
> definitions.

For zero angle cos_phi=1, for right angle cos_phi=0, for flat angle
cos_phi=-1.

Cheers,
Ulf

-- 
Dr Ulf D Schiller
Centre for Computational Science
University College London
20 Gordon Street
London WC1H 0AJ
United Kingdom