Re: [Apbs-users] straight coulomb calculation in APBS?

[Baker, N. <Nat...@pn...>]

Hi Dan --

This isn't possible because the finite grid size prevents the accurate evaluation of the Coulombic potential as r_i -> 0.  That's why we generally try to remove the Coulomb-like part of the numerical solution and replace it with the correct analytical values instead.

Thanks,
__________________________________________________ 
Nathan Baker 
Pacific Northwest National Laboratory
(509) 375-3997 




> -----Original Message-----
> From: Daniel Ensign [mailto:de...@ma...]
> Sent: Thursday, October 07, 2010 12:07 PM
> To: apbs-users
> Subject: [Apbs-users] straight coulomb calculation in APBS?
> 
> Hi,
> 
> I know I can use the share/tools/manip/coulomb to get the electrostatic
> force on any atom assuming dielectric 1, but is it possible to get the
> straight coulomb potential or field using APBS? By "straight coulomb" I
> mean the potential at r is V(r) = sum_i q_i/r_i, neglecting the charge
> at i.
> 
> The reason: I need to combine 2 PB calculations with the straight
> Coulomb calculation, and to reduce file io (I have lots of files) it
> would be useful to do everything with one invocation of APBS.
> 
> One thing I know I don't know would be to set the potential to zero at
> infinity; it doesn't seem that bcfl can do this.
> 
> Thanks for any help,
> Dan
> 
> --
> Tu ne cede malis, sed contra audentior ito. -- Virgil
> 
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