居然连力场等影响结果的最关键的设置都不说 作者Author: yycpolymer 时间: 2022-11-20 22:06
抱歉老师 下次发帖我注意。我使用的力场是compass力场，有机分子为马来酸酐 体系分子数为200. 首先在nve系综中使用郎之万在500k弛豫100000步。然后是npt下500k 1atm下弛豫50000步，500-100k 1atm 弛豫50000步，100-400k 1atm 升温，通过密度和温度曲线判定熔点，但是发现弛豫过程中，在常温下的密度与所查资料中记载的密度并不一致。文献中为1.5，而计算中为1.6左右，结果偏大，请问各位老师这种情况该怎么处理。下面是我的in文件代码。
# Initialization
units real
boundary p p p
atom_style full
# Dreiding potential information
dimension 3
neighbor 0.4 bin
neigh_modify every 1 delay 0 check yes
#对势类型
pair_style lj/class2/coul/long 10.0
pair_modify mix sixthpower tail yes
#键势类型
bond_style class2
special_bonds lj/coul 0.0 0.0 1.0 dihedral yes
#键角势类型
angle_style class2
#二面角类型
dihedral_style class2
improper_style class2
#kspace类型
kspace_style pppm 0.0001
read_data system.data
include "system.in.settings"
include "system.in.charges"
min_style cg
minimize 1.0e-4 1.0e-6 100 1000
#####################################################
# Equilibration Stage 1 (Langevin dynamics at 500 K)
velocity all create 500.0 1231
fix 1 all nve/limit 0.05
fix 2 all langevin 500.0 500.0 10.0 904297
thermo_style custom step temp press density
thermo 1000
timestep 1
run 100000
unfix 1
unfix 2
write_restart restart.system.dreiding1
#####################################################
# Equilibration Stage 2 (NPT dynamics at 500 K)
fix 1 all npt temp 500.0 500.0 100 iso 1 1 1000 drag 2
fix 2 all momentum 1 linear 1 1 1
thermo_style custom step temp press density
thermo 1000
timestep 1
reset_timestep 0
run 50000
unfix 1
unfix 2
write_restart restart.system.dreiding2
#####################################################
# Equilibration Stage 3 (NPT dynamics from 500 K --> 100 K)
fix 1 all npt temp 500 100 100 iso 1 1 1000 drag 2
fix 2 all momentum 1 linear 1 1 1
thermo_style custom step temp press density
thermo 1000
timestep 1
reset_timestep 0
run 50000
unfix 1
unfix 2
write_restart restart.system.dreiding3
#####################################################
# Equilibration Stage 4 (NPT dynamics at 100 K)
fix 1 all npt temp 100 100 100 iso 1 1 1000 drag 2
fix 2 all momentum 1 linear 1 1 1
thermo_style custom step temp pe press vol density
thermo 1000
timestep 1
reset_timestep 0
run 50000
unfix 1
unfix 2
write_restart restart.system.dreiding4
#升温
fix 1 all npt temp 100 400 100 iso 1 1 1000
thermo 1000
reset_timestep 0
thermo_style custom step temp pe press vol density
dump 2 all custom 100 dump.xyz id type x y z
run 100000
unfix 1