mirror of https://github.com/lammps/lammps.git
98 lines
2.7 KiB
Plaintext
98 lines
2.7 KiB
Plaintext
# GCMC for CO2 molecular fluid, rigid/small dynamics
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# Rigid CO2 TraPPE model
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# [Potoff and J.I. Siepmann, Vapor-liquid equilibria of
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# mixtures containing alkanes, carbon dioxide and
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# nitrogen AIChE J., 47,1676-1682 (2001)].
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# variables available on command line
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variable mu index -8.1
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variable disp index 0.5
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variable temp index 338.0
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variable lbox index 10.0
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variable spacing index 5.0
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# global model settings
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units real
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atom_style full
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boundary p p p
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pair_style lj/cut/coul/long 14
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pair_modify mix arithmetic tail yes
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kspace_style ewald 0.0001
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bond_style harmonic
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angle_style harmonic
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# box, start molecules on simple cubic lattice
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lattice sc ${spacing}
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region box block 0 ${lbox} 0 ${lbox} 0 ${lbox} units box
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create_box 2 box &
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bond/types 1 &
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angle/types 1 &
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extra/bond/per/atom 2 &
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extra/angle/per/atom 1 &
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extra/special/per/atom 2
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molecule co2mol CO2.txt
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create_atoms 0 box mol co2mol 464563 units box
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# rigid CO2 TraPPE model
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pair_coeff 1 1 0.053649 2.8
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pair_coeff 2 2 0.156973 3.05
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bond_coeff 1 0 1.16
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angle_coeff 1 0 180
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# masses
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mass 1 12.0107
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mass 2 15.9994
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# MD settings
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group co2 type 1 2
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neighbor 2.0 bin
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neigh_modify every 1 delay 10 check yes
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velocity all create ${temp} 54654
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timestep 1.0
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# rigid constraints with thermostat
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fix myrigid co2 rigid/small molecule mol co2mol
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# dynamically update fix rigid/nvt/small temperature ndof
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fix_modify myrigid dynamic/dof yes
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# gcmc
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variable tfac equal 5.0/3.0 # (3 trans + 2 rot)/(3 trans)
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fix mygcmc co2 gcmc 100 100 0 0 54341 ${temp} ${mu} ${disp} mol &
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co2mol tfac_insert ${tfac} group co2 rigid myrigid
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# atom counts
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variable carbon atom "type==1"
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variable oxygen atom "type==2"
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group carbon dynamic co2 var carbon
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group oxygen dynamic co2 var oxygen
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variable nC equal count(carbon)
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variable nO equal count(oxygen)
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# output
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variable tacc equal f_mygcmc[2]/(f_mygcmc[1]+0.1)
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variable iacc equal f_mygcmc[4]/(f_mygcmc[3]+0.1)
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variable dacc equal f_mygcmc[6]/(f_mygcmc[5]+0.1)
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variable racc equal f_mygcmc[8]/(f_mygcmc[7]+0.1)
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# dynamically update default temperature ndof
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compute_modify thermo_temp dynamic/dof yes
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thermo_style custom step temp press pe ke density atoms v_iacc v_dacc v_tacc v_racc v_nC v_nO
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thermo 1000
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# run
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run 20000
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