respa level for spring self

Dear users,

I am simulating Orcinol(C7H8O2) using ALL-Atom model (OPLS). The maximum
time step i can use for pure crystal simulation is 0.5fs. If i try to
calculate free energy using EM method high spring constants required for H
in methyl group. Because of that time step while simulating Einstein
crystal is even lesser (roughly 0.1 fs). I am planning to use respa with
spring energy in lower level of respa. Is there any way to treat
spring_self in lower level of respa?

my system consist of roughly 7000 atoms.

thanks in advance..

RAVI KUMAR REDDY A
Research Scholar
IISC, Bangalore.

Dear users,

I am simulating Orcinol(C7H8O2) using ALL-Atom model (OPLS). The maximum
time step i can use for pure crystal simulation is 0.5fs. If i try to
calculate free energy using EM method high spring constants required for H
in methyl group. Because of that time step while simulating Einstein
crystal is even lesser (roughly 0.1 fs). I am planning to use respa with
spring energy in lower level of respa. Is there any way to treat
spring_self in lower level of respa?

not without modifying the LAMMPS source code.

i have an idea how this could be implemented, but i will need to
discuss with steve first, whether this is a viable option.

axel.

FYI,

i have now an implementation of setting the respa level using the
fix_modify command for two fixes (setforce and spring/self). i am
still waiting for steve's comments on my approach, but you can now
access the code in a branch in my personal LAMMPS development
repository at: https://github.com/akohlmey/lammps/tree/respa-for-fixes

axel.

Dear Sir,

Thanks for your response...

I will go through these codes

RAVI KUMAR REDDY A
Research Scholar
IISC, Bangalore.