Hello
I am doing simulations of Silicon cantilever beam (clamped-free end). I calculated the force to be applied on the free end using the formula F=(3EI*x)/(L^3) from strength of materials. For a deflection x = 3 Angstroms I got a Force ‘F’ around 0.069 eV/A. I applied this force and the deflection is not around 3 A but very very huge.
Here is my input file:
units metal
boundary s s s
atom_style atomic
lattice diamond 5.43
# creating simulation box
region my_simul_box block -10 225 -10 35 -10 35 units box
create_box 1 my_simul_box
mass 1 28.0855
# creating regions
region Si_fixed block 0 5.43 0 32.58 0 32.58 units box
region Si_middle block 5.43 216.2 0 32.58 0 32.58 units box
region Si_load block 216.2 217.2 0 32.58 0 32.58 units box
region Si_total union 3 Si_fixed Si_middle Si_load
#create atoms in specified region
create_atoms 1 region Si_total
#create groups
group Gr_Si_fixed region Si_fixed
group Gr_Si_middle region Si_middle
group Gr_Si_load region Si_load
group Gr_Si_mobile union Gr_Si_load Gr_Si_middle
# defining the potential
pair_style tersoff
pair_coeff * * SiCGe.tersoff Si(C)
velocity Gr_Si_mobile create 300.0 5812775 dist gaussian
fix 1 Gr_Si_mobile nvt temp 300.0 300.0 0.1
timestep 0.001
thermo 100
thermo_style custom step temp press pe ke etotal
dump trajectory1 all atom 100 dump.cnt
dump disp_traj Gr_Si_load custom 1000 dump.Amp id type x y z fx fy fz
run 50000
unfix 1
fix 2 Gr_Si_mobile nve
fix 3 Gr_Si_load addforce NULL -0.06 NULL
run 60000
unfix 3
run 200000
Regards
APC
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Maybe that force, which you are calculating via a continuum eq,
is too large for an atomistic model.
Steve