about the box size and deposition rate

Dear all,
     I have a question for asking.
     I prepared two systems: 1) with a simulation box = deposition region 2) simulation box > deposition region
     In both systems, the fix deposit command is same and deposition region is same, only the size of simulation box is changed.
     The results show that, in 1) system , in 10ns the needed injecting atoms can be all deposited , but for 2) system, in 10ns, only half atoms are injected.
     I can not understand why for these two system have this different result. For my understanding the deposit velocity is same and deposition region is same, the deposit results should also be same.

I will be appreciate it if anyone can give me a suggestion.

Best
Xiaojing

I'm guessing all the atoms are deposited, but some are leaving the surface
and you are losing them, hence it appears only half your atoms
are staying for long periods of time. The fix deposit doc
page talks about this.

Steve

Many thanks for reply.

But the true situation is the final atoms is different, for in 1) the 100 atoms deposited, and the final atom number is 2000 for example. While in 2) only 50 deposited and final number for the system is 1950. I use the ppf condition, how can I loose them ?

Xiaojing

Because if atoms move across the +z boundary, they
will be lost. Read the boundary doc page and fix deposit
doc page. You need a wall in the +z direction to prevent
that from happening.

Steve

I have :"fix 6 all wall/reflect zlo EDGE zhi EDGE"

this command

the reason I think is the larger box reduce the deposition rate, I try to elongate the simulation time to see.
But I still do not understand

XJ

If by deposition rate you mean atoms/time then that doesn't
depend on the box size. So long as you are not getting
messages during the run that it coudn't deposit atoms,
then it is depositing all the atoms you requested.

Steve