How to instantiate a replica exchange MD simulation with different initial configurations?

LAMMPS LAMMPS General Discussion
,
1

Hello,

I am running replica-exchange molecular dynamics (REMD) in LAMMPS. To obtain accurate free energy estimates, I will likely need to run my REMD calculation for a long period of time. To further improve sampling over different temperatures I want to run simulations with different initial configurations.

I want to run REMD simulations from 275K to 360K with 40 replicas. Each simulation on an even partition index number must start with from State 1 sys.1.data while each odd number must begin with State 2 sys.2.data. Alternatively, I am also thinking about starting the first 20 simulations from State 1 and the latter 20 from State 2. Fundamentally, I want to understand how I can assign a different initial state to a different replica.

How can I do this? Right now, I am starting all the simulations from the same state sys.data.

I have attached my input file (in.npt.entire.lammps), datafile (sys.data), and settingsfile (sys.settings) to this message. I am aware that the input file only has 35 replicas defined, it is only a test case.

sys.data (6.2 MB)
sys.settings (4.8 KB)
in.npt.entire.lammps (3.6 KB)

2

You can use a “world” style variable.

3

Hi @akohlmey. I am doing that for my temperatures. Are you saying that I should employ a world style variable that alternates/first 20 entries are State 1 and then latter 20 entries are State 2, and then gets fed into ‘read_data’?