kim_init MEAM_LAMMPS_EtesamiAsadi_2018_Fe__MO_549900287421_000 metal unit_conversion_mode # Set logfile log output/lmp_T333.15.log # periodic boundary conditions along all three dimensions boundary p p p # Set neighbor skin variable neigh_skin equal 2.0*\${_u_distance} neighbor \${neigh_skin} bin # create a supercell with cubic lattice (fcc, bcc, sc, or diamond) # using 10*10*10 conventional (orthogonal) unit cells variable latticeconst_converted equal 2.851000025868416*\${_u_distance} lattice bcc \${latticeconst_converted} region simbox block 0 10 0 10 0 10 units lattice create_box 1 simbox create_atoms 1 box variable mass_converted equal 55.845*\${_u_mass} kim_interactions Fe mass 1 \${mass_converted} # initial volume variable v equal vol # assign formula variable V0 equal \${v} # evaluate initial value variable V0_metal equal \${V0}/(\${_u_distance}*\${_u_distance}*\${_u_distance}) variable V0_metal_times1000 equal \${V0_metal}*1000 print "Initial system volume: \${V0_metal} Angstroms^3" # set the time step to 0.001 picoseconds variable timestep_converted equal 0.001*\${_u_time} timestep \${timestep_converted} variable temp_converted equal 333.15*\${_u_temperature} variable Tdamp_converted equal 0.1*\${_u_time} variable press_converted equal 0.0*\${_u_pressure} variable Pdamp_converted equal 1*\${_u_time} # create initial velocities consistent with the chosen temperature velocity all create \${temp_converted} 17 mom yes rot yes # set NPT ensemble for all atoms fix ensemble all npt temp \${temp_converted} \${temp_converted} \${Tdamp_converted} & iso \${press_converted} \${press_converted} \${Pdamp_converted} # compute the time averages of pressure, temperature, and volume, respectively # ignore the first 5000 timesteps variable etotal_metal equal etotal/\${_u_energy} variable pe_metal equal pe/\${_u_energy} variable T_metal equal temp/\${_u_temperature} variable V_metal equal vol/(\${_u_distance}*\${_u_distance}*\${_u_distance}) variable P_metal equal press/\${_u_pressure} fix avgmyTemp all ave/time 5 20 100 v_T_metal ave running start 5000 fix avgmyPress all ave/time 5 20 100 v_P_metal ave running start 5000 fix avgmyVol all ave/time 5 20 100 v_V_metal ave running start 5000 # extract fix quantities into variables so they can be used in if-else logic later. variable T equal f_avgmyTemp variable P equal f_avgmyPress variable V equal f_avgmyVol # set error bounds for temperature and pressure in original metal units (K and bar) variable T_low equal "333.15 - 0.2" variable T_up equal "333.15 + 0.2" variable P_low equal "0.0 - 0.2" variable P_up equal "0.0 + 0.2" # print to logfile every 1000 timesteps thermo_style custom step etotal v_etotal_metal pe v_pe_metal & temp v_T_metal vol v_V_metal press v_P_metal thermo 1000 # Run a simulation for at most 2000*1000 timesteps. At each 1000th time step, check # whether the temperature and pressure have converged. If yes, break. label top variable a loop 2000 run 1000 if "\${V_metal}>\${V0_metal_times1000}" then "jump SELF unstable" if "\${T}>\${T_low} && \${T}<\${T_up} && \${P}>\${P_low} && \${P}<\${P_up}" then "jump SELF break" print "flag: Temp = \${T}, Press = \${P}" next a jump SELF top label break # Write final averaged volume to file if temperature and volume have converged; otherwise wirte a # flag to indicate non-convergence. variable myStep equal step if "\${myStep} < 2000000" then "print '\${V}' file output/vol_T333.15.out" & else "print 'not_converged' file output/vol_T333.15.out" print "LAMMPS calculation completed" quit 0 # unstable label unstable print "ERROR: System volume \${V_metal} A^3 has become larger than \${V0_metal_times1000} A^3. Aborting calculation."