lammps问题-关于NVT与NVE系综产生的不同

article/2025/9/21 21:01:03

相同的材料构型，在不同的系综下产生如下不同的结果：
1.NVE系综下：
在这里插入图片描述
2.NVT系综如下：

产生的不同结果如上，原脚本如下：
1.
shell mkdir initial-comp
shell mkdir config-comp
shell mkdir restart-comp
#--------------------------DEFINITION-------------------
units metal
dimension 3
boundary s s s
atom_style atomic

read_data Ti.data
region 1 block INF INF INF INF INF 27 units box
region 2 block INF INF INF INF 319 INF units box
group bottom region 1
group upper region 2
group mobile subtract all bottom upper
group boundary union bottom upper
#---------- Define Interatomic Potential ---------------------
pair_style eam/fs
pair_coeff * * Ti.eam.fs Ti

#-----------------------------setting------------------------
compute eng all pe/atom
compute 1 all stress/atom NULL
compute v all voronoi/atom
variable e1 equal “step”
variable e2 equal “pe”
variable e3 equal “temp”
#------------------------------------------------CUT------------------------------------------------------
delete_atoms overlap 2 all all compress yes
#----------------------------EQUILIBRATION---------------------
timestep 0.002
velocity mobile create 300.0 12345

min_style cg
minimize 1e-18 1e-18 100000 100000
fix 2 boundary setforce 0.0 0.0 0.0
fix 1 all nve
fix 3 mobile temp/rescale 10 300.0 300.0 10.0 1.0

dump 1 all custom 10000 ./initial-comp/relax.*.dump id type x y z
fix def2 all print 100 “${e1} ${e2} ${e3}” file initial-pe-comp screen no
thermo 2000
thermo_style custom step lx ly lz press pe temp

run 50000
undump 1
unfix def2
variable tmp equal “lz”
variable L0 equal ${tmp}
print “Initial Length, L0: ${L0}”

#-------------------------COMPRESSION---------------------------------
reset_timestep 0
timestep 0.002
dump 2 all custom 500 ./config-comp/comp..dump id type x y z c_1[] c_v[]
restart 500000 ./restart-comp/compression..equil

variable strain equal “-(lz - v_L0)/v_L0”
variable e1 equal “v_strain”
variable s1 equal “pzz/10000”
variable s2 equal “pxx/10000”
variable s3 equal “pyy/10000”

#variable s2 equal “4v_s1lx/(ly*PI)”
fix def1 all print 1000 “${e1} ${s1} ${s2} ${s3}” file Ti1000-comp screen no
thermo 100000
thermo_style custom step temp ke pe press

velocity upper set 0 0 -0.15
velocity mobile ramp vz 0.0 -0.15 z 29 317 sum yes
run 200000

print “ALL DONE!”

shell mkdir initial-comp
shell mkdir config-comp
shell mkdir restart-comp
#--------------------------DEFINITION-------------------
units metal
dimension 3
boundary s s s
atom_style atomic

min_style cg
minimize 1e-18 1e-18 100000 100000
fix 2 boundary setforce 0.0 0.0 0.0
fix 1 all nvt temp 300 300 100

run 50000
undump 1
unfix def2
variable tmp equal “lz”
variable L0 equal ${tmp}
print “Initial Length, L0: ${L0}”

variable strain equal “-(lz - v_L0)/v_L0”
variable e1 equal “v_strain”
variable s1 equal “pzz/10000”
variable s2 equal “pxx/10000”
variable s3 equal “pyy/10000”

#variable s2 equal “4v_s1lx/(ly*PI)”
fix def1 all print 1000 “${e1} ${s1} ${s2} ${s3}” file Ti1000-comp screen no
thermo 100000
thermo_style custom step temp ke pe press

velocity upper set 0 0 -0.15
velocity mobile ramp vz 0.0 -0.15 z 29 317 sum yes
run 200000

print “ALL DONE!”