# problem about if lammps can simulate the progress

hi everyone:
i want to use molecular dynamic simulation method to simulate the progress of laser cutting. i’ve searched the internet about this study , m i’m not sure if lammps can

Q:
Emily

hi everyone:
i want to use molecular dynamic simulation method to simulate the progress of laser cutting. i’ve searched the internet about this study , most of the literature is simulated using the finite element method, i’m not sure if lammps can

Q:

theoretically would be possible to something like you are describing, but practically, it makes no sense, at least not with an atomic scale model. the length and time scales​ are such, that there is no computer large and fast enough to simulate such a system during your lifetime (and that of your children and grandchildren). not by many orders of magnitude.

​axel.​

hi Axel and others
of course i know that molecular dynamic simulation can only work in an atomic scale model. i just want to explore the physical mechanism of laser interaction with special material in a small system(maybe millions of atoms). and d to use laser to cut the material.
Q :i am not sure if lammps can simulate all progresses including laser loading which i want to use finite element method to do and energy transfer. in other words,do i have to use Ansys to calculate the distribution of laser energy before Lammps?

emily,

let me re-iterate: you still don’t understand time and length scales of MD simulations properly, which is why what you describe you want to do is pointless. to model and understand the macroscopic process, you do not need to model it microscopically, you just need the various material properties, which you can obtain from a variety of calculations (including solid state electronic structure calculations), none of which need to model the laser cutting itself. yes, there are ways to model heat transfer from radiation to atoms (fix ttm, fix ttm/mod, fix atc), but those do not address the time or length scale issues. due to the separation of the scales you have the situation, that from the view of the (macroscopic) finite element system: only time and system averaged properties of the atomic scale data matter, not the dynamics itself; and from the view of the atomic scale system, the macroscopic behavior is so much slower, that you can assume static behavior and then just do a parameter scan.

in short, it is not a matter of capability, it is a matter of common sense and understanding the difference between microscopic and macroscopic properties and behavior. if you still don’t understand what i am talking about, please have some significant “quality time” with a text book on statistical thermodynamics before doing (and asking about) anything else in this matter.

axel.