Respected lammps user, I am using lammps Aug 2023, mpi version on windows 10 and getting a problem of updating the velocity of particles as I applied the velocity in x direction while the particles move at angle of 45 degree to x direction furthermore, I am using the restart file before writing this file all the fixes nvt integrals are removed except velocity seed velocity silver create 1100 1234567654321 mom yes rot yes dist gaussian loop geom, using commands to move particles in x direction are given. Kindly assist
fix 4 silver nve
velocity silver set 0.5 0 0 units box`
Is this command suitable to retain the velocity for the whole simulation as but this stops the vibrational motion of atoms…..
fix 9 silver move linear 0.5 0 0
The problem is fixed only if higher velocity magnitudes from 5 and onwards are applied. why and how it doesn’t work for 0.5 and enen at 200000 th timestep the Ag stopped moving further and retained the same position till 700000 th run at then reverse its bulk motion confusing updating bulk motion?
For more clarification a complete script I am adding here describing the wetting of silver on diamond after the wetting is completed a restart file is taken as an output and rerun for the shear as below
read_restart restartforshearing1
#here pair style is defined in the script
velocity silver create 1100 1234567654321 mom yes rot yes dist gaussian loop geom
#velocity silver create 1100 12345 13531 1234321 135135 12353210 123454321（alternative best seed) mom no rot no 1234567654321 at 1020
run 0
velocity silver scale 1100
fix 11 nvt temp 1100 1100 1.0
run 10
unfix 11
#shearing of molten silver on diamond
fix 7 silver nvt temp 1100 1100 1.0
unfix 7
fix 4 silver nve
velocity silver set 0.5 0 0 sum yes units box
#velocity mobile ramp vx 0.0 1.0 y 1.4 8.6 sum yes
#unfix 1
# The seperate slab or either silver compute should be used otherwise for the all it will be zero or very less when setforce 0 command is waived and either of the group will give the same result. Either slab or either silver group or either all give the same results but keeping setforce 0 on the slab there will be no dump ovito output for the slab or silver group if set zero at either of the interfacets groups.
compute force1 silver property/atom fx
compute force2 silver property/atom fy
compute force3 silver property/atom fz
compute shearforcex silver reduce sum c_force1
compute shearforcey silver reduce sum c_force2
compute shearforcez silver reduce sum c_force3
compute shearforce1x silver reduce ave c_force1
compute shearforce1y silver reduce ave c_force2
compute shearforce1z silver reduce ave c_force3
compute peratom all stress/atom NULL
compute p all reduce sum c_peratom[1] c_peratom[2] c_peratom[3] c_peratom[4] c_peratom[5] c_peratom[6]
#compute f_silvdiam silver group/group slab
#variable forcex equal c_f_silvdiam[2]
#similar as property per atom
#variable Force atom fx
#thermo_style custom step temp lx ly lz press pxx pyy pzz pe press c_shearforcex c_shearforce1x c_shearforcey c_shearforce1y c_shearforcez c_shearforce1z
thermo 10
thermo_style custom step temp c_shearforcex c_shearforcey c_shearforcez evdwl enthalpy etotal pe ke pxy vol density
variable natoms_silver equal count(silver)
#compute cvor silver voronoi/atom
#compute peratomvol silver reduce sum c_cvor[1]
#variable peratomvol1 atom c_cvor[1]
#variable totalvornoi equal c_peratomvol*1
variable shearforcerx equal c_shearforcex*1
variable shearforcer1x equal c_shearforce1x*1
variable shearforcery equal c_shearforcey
variable shearforcer1y equal c_shearforce1y
variable shearforcerz equal c_shearforcez
variable shearforcer1z equal c_shearforce1z
compute disp1 silver property/atom x
compute disp2 silver property/atom y
variable disp1a equal c_disp1
variable disp2a equal c_disp2
compute disp silver displace/atom
compute Dx silver reduce sum c_disp[1]
compute Dy silver reduce sum c_disp[2]
variable Dx1 equal c_Dx
variable Dy1 equal c_Dy
variable shearstrainalpha equal v_Dx1/3.077
variable varshearstrain equal v_Dx1/(3.077-v_Dy1)
variable veloc equal 1
variable dt equal dt
variable steps equal 1*step
variable disp equal v_veloc*dt*step
variable shearstrain equal v_disp/3.077
variable Fx_total equal c_shearforce1x*v_natoms_silver
variable Fy_total equal c_shearforce1y*v_natoms_silver
variable Fz_total equal c_shearforce1z*v_natoms_silver
#variable p1 equal “-pxx/10000”
#variable p2 equal “-pyy/10000”
#variable p3 equal “-pzz/10000”
variable p4 equal “-pxy/10000”
#variable p5 equal “-pyz/10000”
#variable p6 equal “-pxz/10000”
#fix 3 mobile temp/rescale 10 300.0 300.0 10.0 1.0
#fix_modify 3 temp new2d
#fix def_print all print 100 "${p1} ${p2} ${p3} ${p4} ${p5} ${p6} ${Force}" file mg001.defo.txt screen no
#fix statdump all print 1 "${p1} ${p2} ${p3} ${p4} ${p5} ${p6} ${Force} ${forcex}" screen no file dump.stat
#fix statdump all print 1 "${steps} ${p4} ${shearstrain} ${disp} ${shearforcerx} ${shearforcer1x} ${shearforcery} ${shearforcer1y} ${shearforcerz} ${shearforcer1z} ${Fx_total} ${shearstrainalpha} ${Dx1} ${Dy1} ${varshearstrain}" screen no file dump.stat
fix statdump1 all print 1 "${steps} ${shearstrain} ${shearstrainalpha} ${disp}" screen no file dump.stat1
fix statdump2 all print 1 "${steps} ${shearforcerx} ${shearforcery} ${shearforcerz}" screen no file dump.stat2
fix statdump3 all print 1 "${steps} ${Fx_total} ${Dx1} ${Dy1} ${varshearstrain}" screen no file dump.stat3
dump 1 all custom 5 dump.indent_loading.*.custom id type x y z c_peratom[1] c_peratom[2] c_peratom[3] c_peratom[4] c_peratom[5] c_peratom[6] c_force1 c_force2 c_force3 c_disp[1] c_disp[2] fx fy fz
dump shear all atom 100 m.facet3ashear
reset_timestep 0
run 1100000
write_restart restartaftershear
Thanks