Hello,
I’ve noticed in my LAMMPS simulations that van der Waals energy rises as temperature increases. Is this common or specific to my setup?
Fix npt temp 300 600 100.0 iso 1.0 1.0 1000.0
Timestep 1.0
run 100000
You are not providing any specific information about your setup, so how can anybody answer your question without being a mind reader?
Generally, please think about what is supposed to happen during equilibration, particularly when you start from an ideal geometry?
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As an additional suggestion, it is trivial to modify any of the examples from the examples folder to include an increasing temperature, and see what that does to the potential energy, and then to consult any standard mechanical textbook about the function \langle U \rangle (T) compared between canonical ensembles at different temperatures.
You may provide your whole input script.
Thank you all for replying. This is my input file.
——————————————————
units real
atom_style full
boundary p p p
bond_style harmonic
angle_style harmonic
dihedral_style harmonic
pair_style lj/cut/coul/long 12.0
special_bond lj/coul 0.0 0.0 1.0
kspace_style pppm 1.0e-4
neighbor 2.0 bin
neigh_modify delay 0 every 1
read_data r10000.txt
pair_coeff 1 1 0.1799 3.786
pair_coeff 1 2 0.1920 3.371
pair_coeff 1 3 0.3244 3.586
pair_coeff 2 2 0.2049 2.955
pair_coeff 2 3 0.3462 3.170
pair_coeff 3 3 0.5848 3.358
bond_coeff 1 189.65 1.88
bond_coeff 2 350.12 1.60
angle_coeff 1 49.97 109.24
angle_coeff 2 49.97 109.5
angle_coeff 3 94.5 109.5
angle_coeff 4 14.14 144.0
dihedral_coeff 1 0.9006 1 3
dihedral_coeff 2 0.9006 1 3
thermo 1000
thermo_style custom step time temp density press vol pe evdwl ecoul elong
dump 2 all atom 10000 P_1000_1.dump
fix 3 all npt temp 298.15 348.15 (100.0*dt) iso 1.0 1.0 (1000.0*dt)
timestem 1.0
run 1000000
(Sorry I misunderstood your post actually, I was talking about some LJ thing and it was not actually what you were asking)