Need Information about melting and quenching Al

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1

Dear to all,### I want to melt Aluminum metal at about 800K and then quench it to 300K and see the atom configuration and properties of metal at this temperature with LAMMPS:### I use this LAMMPS code and I want to know is the simulation process true or not?### ### ### ### a) This structure is initialized at 800 K under an isothermal-isobaric (NPT) ensemble at a pressure of 0 MPa for 50 picoseconds (ps).### b) Subsequently, we rapidly quench the alloy to 300 K.### c) The structure is allowed to relax for an An additional 90 ps under the microcanonical ensemble (NVT).### ### My input LAMMPS file is:### ### # Initial configuration of an Al atoms### ### boundary p p p### dimension 3### units metal### atom_style atomic### ### #################################### BOX### region box block -12 12 -12 12 -12 12 units box### create_box 1 box### ### ##################################### CREATE ATOMS### lattice fcc 4.05### region cube block -5 5 -5 5 -5 5 units box### create_atoms 1 region cube### ### ##################################### MASS### mass 1 26.98### velocity all create 1 12345 mom yes rot yes dist uniform### ### ##################################### POTENTIAL### pair_style lj/cut 8.5### pair_coeff * * 0.0104 3.4### ### ##################################### melting### fix 1 all npt temp 800 800 1 iso 0 0 1000### ### ##################################### TIME STEP### timestep 0.001### ### ##################################### THERMODYNAMIC### thermo 2000### ### dump 1 all xyz 100 dump.xyz### run 50000### ##################################### quenching### fix 2 all npt temp 800 300 1 iso 0 0 100### ### dump 2 all xyz 100 dump.xyz### run 5000### ### ### ##################################### relax### fix 3 all nvt temp 300 300 100### ### dump 3 all xyz 100 dump.xyz### run 90000### ### ###

Al.in (1.44 KB)

2

​You should unfix your previous fixes after each run command.

-Keith

3

Dear to all,### I want to melt Aluminum metal at about 800K and then quench it to 300K and see the atom configuration and properties of metal at this temperature with LAMMPS:### I use this LAMMPS code and I want to know is the simulation process true or not?

whether you get the correct results or not, is something that you will have to verify yourself. nobody will do this for you (and how would this sound in a paper when you write “some random dude on a mailing confirmed that my input was good”?).

thus watch the output that LAMMPS is printing and check for any warnings.
validate the physical properties (e.g. density, radial distribution function, self-diffusion coefficient) of your simulated system with documented properties of the model you are using and the real material.
please note, that there are better models for metals than the lennard-jones potential.

### ### ### a) This structure is initialized at 800 K under an isothermal-isobaric (NPT) ensemble at a pressure of 0 MPa for 50 picoseconds (ps).

is the equilibrium density at 800K the density you want?

b) Subsequently, we rapidly quench the alloy to 300 K.

nose-hoover thermostats are notoriously inefficient for rapid transfer or kinetic energy. that is because they are designed to model systems at equilibrium. you want a dissipative termostat, of which LAMMPS contains several.

axel.