Hello Everyone,
I’ve been working on Molecular Dynamics of Nano-indentation of CNT reinforced polymer.
556 number of stoichiometric mixtures (1 Epon 862 + DETDA) are duplicated around the one SWCNT in the amorphous cuboid specimen (matrix) which is constructed with a size of 300 × 300 × 150 Å3 and the periodic boundary condition is applied in all the three directions.
shrinking process is performed on the box in x and y directions to achieve the required density 1.2 g/cm3 while a force field (50 kcal/Å) of cylindrical shape is put around the CNT using fix indent command to avoid the CNT collapse during shrinking (before indentation start).
But CNT is wrinkling at initial stage of shrinking (using fix deform command).
I did try with different force fields 50 , 70, and 100 Kcal/Å for “fix indent” , still same problem.
Now i’m using 500 Kcal/Å (running).
Please help me to keep CNT without any wrinkle throughout my shrinking process.
I’m attaching sliced image file of my system.
Thanks in advance!
Ashok Kumar Bevara
Hello Everyone,
I've been working on Molecular Dynamics of Nano-indentation of CNT
reinforced polymer.
556 number of stoichiometric mixtures (1 Epon 862 + DETDA) are duplicated
around the one SWCNT in the amorphous cuboid specimen (matrix) which is
constructed with a size of 300 × 300 × 150 Å3 and the periodic boundary
condition is applied in all the three directions.
shrinking process is performed on the box in x and y directions to achieve
the required density 1.2 g/cm3 while a force field (50 kcal/Å) of
cylindrical shape is put around the CNT using fix indent command to avoid
the CNT collapse during shrinking (before indentation start).
But CNT is wrinkling at initial stage of shrinking (using fix deform
command).
I did try with different force fields 50 , 70, and 100 Kcal/Å for "fix
indent" , still same problem.
Now i'm using 500 Kcal/Å (running).
Please help me to keep CNT without any wrinkle throughout my shrinking
process.
it is impossible to give any advice without knowing all the details of
the simulation, but if everything is how you claim it is, then the
most likely explanation is that either your topology (bonds, angles,
dihedrals) is wrong somewhere, or your force field.
set up a system with only the CNT and run a simulation on that without
using fix deform. does it maintain its shape? if not, you need to find
out why. if yes, then you need to investigate whether there is
something wrong with the interactions with the other molecules, or
with how you do the compression.
axel.
Dr. Axel and all
As you suggested I have tried with a system with “only CNT”, i dont see any shape change before minimization.
but i can see shape change during minimization and also after using “fix indent”
I have a quick question:
If I have one vertical CNT at center of the box with 7.35A radius and polymer around it.
and if i’m using
min_style cg
minimize 1.0e-5 1.0e-7 1000 1000
fix 20 1 indent 1000.0 cylinder z 0.0 0.0 11.0 side out
here 1 representing all polymer molecules (except CNT) and Radius of cylinder (11.0 A) is more than the Radius of CNT (7.35 A).
is this indenter work on my CNT apart from Polymer?
(please look at the attached image if needed)
Thanks in advance
Ashok Kumar Bevara
Dr. Axel and all
As you suggested I have tried with a system with "only CNT", i dont see any
shape change before minimization.
but i can see shape change during minimization and also after using "fix
indent"
then you must be doing something wrong, or your potential parameters
are wrong or your topology data or ....
I have a quick question:
If I have one vertical CNT at center of the box with 7.35A radius and
polymer around it.
and if i'm using
min_style cg
minimize 1.0e-5 1.0e-7 1000 1000
fix 20 1 indent 1000.0 cylinder z 0.0 0.0 11.0 side out
here 1 representing all polymer molecules (except CNT) and Radius of
cylinder (11.0 A) is more than the Radius of CNT (7.35 A).
is this indenter work on my CNT apart from Polymer?
(please look at the attached image if needed)
i have no idea what you are asking and cannot make much sense of the
picture. ...and in all honesty, you have worn out my willingness to
answer questions. you should talk to your adviser or whoever your
adviser has designated to teach you MD.
your problems are obviously due to your lack of fundamental training
in MD. i don't have the time and patience to teach you this over
e-mail.