[lammps-users] tail corrections

Hello, all,

Has anyone used the command:
pair_style lj/coul cut long cutoff

Although the manual says tail correction of energy and pressure can be calculated if setting of pair_modify is changed, it actually can not. The ‘etail’ is always 0 even if I use ‘pair_modify tail yes’.

What’s wrong?

The following is my input:

units real
dimension 3
atom_style full

neighbor 2.0 bin
neigh_modify delay 0 every 5

boundary p p p

read_data VolNrm.dme

pair_style lj/coul cut long 9.0

-------- LJ for 1-CH3 2-O 3-CH2 and Coulombic ---------

pair_coeff 1 1 0.194746 3.75
pair_coeff 2 2 0.109296 2.80
pair_coeff 3 3 0.0914113 3.95
pair_modify mix arithmetic # LJ mixing rules
pair_modify tail yes # enable long-range tail correction to energy and pressure of LJ portion
special_bonds lj/coul 0.0 0.0 0.5 dihedral no # 1-2,1-3,1-4 interactions
kspace_style pppm 0.0001 # long-range Coulombic force

-------- bond definition and fixed length, 1-CHxCHy, 2-CHxO --------

bond_style harmonic
bond_coeff 1 0.0 1.54 # Non bond energy calculated because of SHAKE
bond_coeff 2 0.0 1.41

#fix 1 sub shake 0.0001 20 50000 b 1 2 # record SHAKE statistics every 100ps

--------- angle potentials ----------

angle_style harmonic
angle_coeff 1 60.0136 112 #394026.226 112
angle_coeff 2 49.9783 112 #328137.843 112

---------- dihedral potentials -----------

dihedral_style multi/harmonic
dihedral_coeff 1 0.38456 -5.06931 -1.86879 5.11472 1.53537
dihedral_coeff 2 0.530115 -4.21128 1.99618 8.03059 1.20913

--------- system ------------------

velocity all create 303.15 2349852

compute MyPress all pressure thermo_temp

fix 2 all nvt 303.15 303.15 100

-------------- calculation of energy ---------------

thermo_style custom step pe evdwl etail ecoul elong ebond eangle edihed press
thermo_modify press MyPress

thermo 5
log log.VolNrm

run 1

Hello, all,
Has anyone used the command:
pair_style lj/coul cut long cutoff

the lj/coul pair style is part of the user-ewaldn package
and same as all user packages only supported by the
original author.

Although the manual says tail correction of energy and pressure can be
calculated if setting of pair_modify is changed, it actually can not. The
'etail' is always 0 even if I use 'pair_modify tail yes'.
What's wrong?

obviously, in contrast to documentation the tail correction has
not been implemented. a quick search through the source code
will confirm this.

axel.

The doc page is incorrect - this potential does not
implement LJ tail corrections. I don't think there
is any reason to use this potential if you don't want
long-range LJ, in which case
you wouldn't need tail corrections. You can just use
pair_style lj/cut/coul/long.

Steve