[Xplor-nih] noePot

[Andreas Ceymann]

Hi,

i do some calculations with mainly noe restrained structures. Therefore i use 
a script based on the example script anneal.py. The formula for noePot 
according to the reference manual is:

>The energy function is defined as
> 
>        if pot=HARD or  r<rSwitch: 
>                scale * r^hardExp
>        pot=SOFT and r>rSwitch: 
>                scale * (a + b / r^softExp + asympSlope * r)
> 
>        where
>        b =  rSwitch^(softExp+1) * 
>            (asympSlope - hardExp * rSwitch^(hardExp-1)) / softExp
>        a = rSwitch^hardExp - b * rSwitch^(-softExp) - 
>            asympSlope * rSwitch;

I calculated this potential as a function of r and the result is a potential 
that is partially negative and that is not continuous at rSwitch. So i guess 
this formula can't be the one which is used for the noe calculations. What is 
the function used by the program?

I wonder why the parameters in anneal.py differ so much from the default 
values. What is the reason for this?

Thanks!
Andreas