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RE: [ESPResSo-devel] shifts
From: |
Limbach, Hans Joerg, LAUSANNE, NRC-FS |
Subject: |
RE: [ESPResSo-devel] shifts |
Date: |
Tue, 9 Oct 2007 14:50:19 +0200 |
Hi,
The implementation (which in this case at least is consistent with the
documentation) is
frac = lj_sigma / (r_ij - lj_offset )
E_LJ = 4*lj_eps*( frac^12 - frac^6 + shift )
In other words the shift has to be
fcut = lj_sigma / ( lj_cut - lj_offset )
shift = - ( fcut^12 - fcut^6 )
I have added a procedure to ABHmath.tcl which does exactly this:
calc_lj_shift <lj_sigma> <lj_cutoff> <lj_offset>
(And I also added the documentation in the user guide ;-) )
It's probably good to use that in all scripts (Axel you can hear me?)
Hanjo
> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden On
> Behalf Of Axel Arnold
> Sent: mardi, 9. octobre 2007 13:42
> To: ESPResSo developers' mailing list
> Subject: [ESPResSo-devel] shifts
>
> Hi all,
>
> Peter Kosovan has a point: this is the current state of
> shifting in our sample
> scripts:
> espresso_logo.tcl:set lj1_shift $lj1_eps
> kremerGrest.tcl:set lj1_shift 0.25
> lj_liquid.tcl:set lj1_shift $lj1_eps
> maggs.tcl:set lj1_shift [expr 0.25*$lj1_eps]
> pe_network.tcl:set LJ_shift 0
> pe_solution.tcl:set lj1_shift [expr
> -4.0*$lj1_epsilon*(pow($lj1_cut,-12)-pow($lj1_cut,-6))]
> pe_solution.tcl:set lj2_shift [expr
> -4.0*$lj2_epsilon*(pow($lj2_cut,-12)-pow($lj2_cut,-6))]
>
> So, kremerGrest.tcl is the only correct sample, but we have a
> whole variety of wrong examples... Does anybody see a problem
> if I just fix all the scripts?
>
> Many regards,
> Axel
>
> --
> Dr. Axel Arnold
> FOM Institute for Atomic and Molecular Physics
> Kruislaan 407 Phone: +31 20 6081 275
> 1098 SJ Amsterdam, The Netherlands E-mail: address@hidden
>
> _______________________________________________
> ESPResSo-devel mailing list
> address@hidden
> https://fias.uni-frankfurt.de/mailman/listinfo/espresso-devel
>
- [ESPResSo-devel] shifts, Axel Arnold, 2007/10/09
- RE: [ESPResSo-devel] shifts,
Limbach, Hans Joerg, LAUSANNE, NRC-FS <=