[gmx-users] Cutoff: PME vs Shift

[Juliette N.]

Hello all,

I am trying to compare PME and shift electrostatics methods for my
hydrocarbon system. In both cases rlist               =  1.35 , but in case
of PME rcoulomb            =  1.35 while for shift **
rcoulomb            =  1.1. I see no significant change (less than 1%) in
total system potential, however I would like to know if I can conclude that
electrostatic energy is insensitive to cutoff distance of rcoulomb as a
result of change from 1.1 (shift) to 1.35 (PME)?*
*

**

Is this a correct interpretation?

Thank you for your help,

*
*

*CASE 1:*

*coulombtype         =  PME*

vdw-type           =  Shift

;          Cut-offs

rlist               =  1.35

*rcoulomb            =  1.35   *

rvdw                =  1.1

rcoulomb-switch     =  1

rvdw-switch         =  1

* *

*CASE 2:*

*coulombtype         = Shift                 *

vdw-type           =  Shift





;          Cut-offs

rlist               =  1.35

*rcoulomb            =  1.1*

rvdw                =  1.1



rcoulomb-switch     =  1
rvdw-switch         =  1

Thanks for your comments,