[gmx-users] Dielectric constant

[avinash kumar]

Dear users,

            I am trying to simulate electroosmotic flow using GROMACS.
The liquid is water and I am trying to find the dielectric constant of
water. I am just getting a value of dielectric constant of 10. i am
expecting 80 for water. I am attaching my mdp . I would be grateful if
somebody points some mistake.

title                    = md
cpp                      = cpp
include                  = -I../top
define                   =


integrator               = md
tinit                    = 0
dt                       = 0.001
nsteps                   = 700000
init_step                = 0
comm-mode                = Linear
nstcomm                  = 500
comm-grps                =
bd-fric                  = 0
ld-seed                  = 1993
emtol                    = 10
emstep                   = 0.01
niter                    = 20
fcstep                   = 0
nstcgsteep               = 1000
nbfgscorr                = 10
nstxout                  = 100
nstvout                  = 100
nstfout                  = 100
nstcheckpoint            = 20
nstlog                   = 100
nstenergy                = 10
nstxtcout                = 0
xtc-precision            = 1000
xtc-grps                 =
energygrps               = WA WA1 WA2 SOL NA+
nstlist                  = 10
ns_type                  = simple
pbc                      = xyz
rlist                    = 0.7
domain-decomposition     = no
coulombtype              = PME
rcoulomb-switch          = 0
rcoulomb                 = 0.7
epsilon_r                = 1
epsilon_rf               = 1
vdw-type                 = Cut-off
rvdw-switch              = 0
rvdw                     = 0.7
DispCorr                 = No
table-extension          = 1
energygrp_table          =
fourierspacing           = 0.12
fourier_nx               = 0
fourier_ny               = 0
fourier_nz               = 0
pme_order                = 4
ewald_rtol               = 1e-05
ewald_geometry           = 3dc
epsilon_surface          = 0
optimize_fft             = no

gb_algorithm             = Still
nstgbradii               = 1
rgbradii                 = 2
gb_saltconc              = 0

implicit_solvent         = No

tcoupl                   = Berendsen
tc-grps                  = WA WA1 WA2 SOL NA+
tau_t                    = 0.1   0.1   0.1  0.1  0.1
ref_t                    = 300  300  300  300  300
Pcoupl                   = No
Pcoupltype               = Isotropic
tau-p                    = 1
compressibility          =
ref-p                    =
andersen_seed            = 81513
constraints              = all-bonds
constraint-algorithm     = Lincs
unconstrained-start      = no
Shake-SOR                = no
shake-tol                = 1e-04
lincs-order              = 4
lincs-iter               = 1
lincs-warnangle          = 30
morse                    = no

; ENERGY GROUP EXCLUSIONS
; Pairs of energy groups for which all non-bonded interactions are excluded
energygrp_excl           =


disre                    = No

disre-weighting          = Conservative

disre-mixed              = no
disre-fc                 = 1000
disre-tau                = 0

nstdisreout              = 100

orire                    = no

orire-fc                 = 0
orire-tau                = 0
orire-fitgrp             =

nstorireout              = 100

dihre                    = No
dihre-fc                 = 1000
dihre-tau                = 0

nstdihreout              = 100

; Free energy control stuff
free-energy              = no
init-lambda              = 0
delta-lambda             = 0
sc-alpha                 = 0
sc-power                 = 1
sc-sigma                 = 0.3

; Non-equilibrium MD stuff
acc-grps                 =
accelerate               =
freezegrps               = WA WA1 WA2
freezedim                = y  y  y   y  y  y  y  y  y
cos-acceleration         = 0
deform                   =

; Electric fields
; Format is number of terms (int) and for all terms an amplitude (real)
; and a phase angle (real)
E_x                      = 1 0.1 0
E-xt                     =
E-y                      =
E-yt                     =
E-z                      =
E-zt                     =




-- 
Avinash Kumar.