Lujing,

Please always respond to the list as it can help people asking similar questions in the future. Sergiy(who wrote it) used LAMMPS to carry out these particle aggregation simulations, and to do them you don’t really need anything very special (just use fix langevin). I believe he post processed his data with his own code to get aggregate information, as it takes little effort.

As for PBEs (population balance equations?) you won’t find anything in LAMMPS to do anything but model kernels to use when solving said PBEs.

Eric, thanks very much for you answers. I will try again. And also thanks for your suggestion to respond to the list.

best wishes!

lujing

Dear Eric:

Thank you very much for your email and your paper about brownian dynamics simulation which is computationally effective for studying the aggregation of colloid particles. i have some doubt in “fix langevin” command in lammps. if the frictional coefficient gamma is 0.5, and particle diameter d is 6nm, particle mass is 10000(relative atomic mass),temperature is controlled at 300K, and the time step delta t=0.005 in reduced time units of d*(m/kT)1/2,the units style in lammps is metal, how can I set the damp parameter in " fix langevin " command, and the timestep?

in manu, gamma=m/damp, but i have trouble in converting the units, can you give me some advice? thank you very much!

Xuepeng

Dear Eric:

Thank you very much for your email and your paper about brownian dynamics

simulation which is computationally effective for studying the aggregation

of colloid particles. i have some doubt in "fix langevin" command in

lammps. if the frictional coefficient gamma is 0.5, and particle diameter d

is 6nm, particle mass is 10000(relative atomic mass),temperature is

controlled at 300K, and the time step delta t=0.005 in reduced time units of

d*(m/kT)1/2,the units style in lammps is metal, how can I set the damp

parameter in " fix langevin " command, and the timestep?

in manu, gamma=m/damp, but i have trouble in converting the units, can you

give me some advice? thank you very much!

if you don't know how to convert units, you should see and find

somebody that can teach you how to do it. teaching rather basic skills

via a mailing list is difficult, tedious and inefficient. why don't

you ask one of your colleagues to teach you? or your adviser? or ???

axel.

Hi,axel:

i am sorry that my question is tedious, actually my adviser do not know much about my field research, and i have no one to ask. there are many talent lammps uesers here, and it is a coincidence that some one ask the question that i concern.therefore, i hope someone can give me some advice. i am sorry again!

Xuepeng

Hi,axel:

i am sorry that my question is tedious, actually my adviser do not know much about my field research, and i have no one to ask. there are

Your question about reduced units is not a lammps question, but a basic Physics question and I find it very difficult to believe that there is not a single person in an entire institution that doesn’t know how to convert to and from reduced units.

many talent lammps uesers here, and it is a coincidence that some one ask the question that i concern.therefore, i hope someone can give me some advice. i am sorry again!

Just want to clarify that the paper is not mine. And Axel is right, this is just a physics/math question about unitless/reduced units/nondimensionalized quantities, http://en.wikipedia.org/wiki/Nondimensionalization.

Hi,all:

thank you very much for your advice!

best

Xuepeng