[lammps-users] Problems in NVT simulation

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1

Dear all,

I want to try to do NVT simulation of Cu-Zr nanowire, but...the output
value is obviouly amusing.
The log files are put on the following.

LAMMPS (9 Jan 2009)
# Cu-Zr alloy b2 structure

units metal
atom_style atomic

read_data init-3.txt
orthogonal box = (-100 -20 -20) to (50 20 20)
1 by 1 by 1 processor grid
7856 atoms
mass 1 63.546
mass 2 91.224

velocity all create 100.0 8728
pair_style eam/alloy
pair_coeff * * ../../potentials/CuZr_mm.eam.fs Cu Zr

neighbor 2.0 bin
neigh_modify every 20 delay 0 check no
run_style verlet

fix 1 all nvt 100 100 0.01 drag 1.0
dump id all atom 10 dump.melt
timestep 0.001
thermo 1
thermo_style custom step temp ke pe etotal press
run 1000
Memory usage per processor = 5.74331 Mbytes
Step Temp KinEng PotEng TotEng Press
0 58.649937 59.549536 -6.017978e+14 -6.017978e+14 -9.0362764e+15
1 1.2814507e+21 1.3011062e+21 -1.5457072e+12 1.3011062e+21 5.7905604e+21
2 0 0 1.1924863e+15 1.1924863e+15 8.2020462e+15
3 0 0 3.7829393e+14 3.7829393e+14 8.0599385e+14
4 0 0 1.6091347e+14 1.6091347e+14 3.3592944e+14
5 0 0 2.4162933e+13 2.4162933e+13 -3.8427798e+14
6 0 0 3.210564e+13 3.210564e+13 1.655491e+12
7 0 0 1.5116975e+13 1.5116975e+13 -2.8849444e+14
8 0 0 7.2820291e+12 7.2820291e+12 1.6204298e+13
9 0 0 6.5326396e+12 6.5326396e+12 1.4536724e+13
10 0 0 9.2400521e+12 9.2400521e+12 2.056138e+13
11 0 0 5.9406095e+12 5.9406095e+12 1.3219313e+13
12 0 0 9.7703454e+12 9.7703454e+12 2.1741413e+13
13 0 0 5.115046e+12 5.115046e+12 1.1382231e+13
14 0 0 2.4514948e+12 2.4514948e+12 5.4551767e+12
15 0 0 1.3576798e+13 1.3576798e+13 3.0211706e+13
16 0 0 2.6840773e+12 2.6840773e+12 -2.3787875e+15
17 0 0 6.6557008e+12 6.6557008e+12 1.4810567e+13
18 0 0 3.5327626e+13 3.5327626e+13 7.8612629e+13
19 0 0 1.3483534e+13 1.3483534e+13 3.0004169e+13
ERROR: Lost atoms: original 7856 current 10

Why are the value of pressure , potential energy and total energy large
? Cannot you make them smaller?
Please answer.

Keiju

2

0 58.649937 59.549536 -6.017978e+14 -6.017978e+14 -9.0362764e+15

This line means your intiial geometry of atoms is bad. If you
run dynamics it will blow up. You should also not
be defining mass yourself. The EAM files have the atom
masses in them, and I'm guessing you chose different values,
hence the temp of 100 you set is not what the temp turns
out to be after the EAM file resets the masses.

Steve

2009/10/30 越山 桂樹 <[email protected]...>:

3

Hi, Steve:

Is there any method in LAMMPS to get the total force on a group of molecules due to their non-bonded interactions with other molecules which are not in the group? If I have to change the source code, could you provide some hints about which the best way to implement it?

Thanks a lot for your help!
Leo

4

Compute group/group can calculate this.

Steve