[lammps-users] Setting up the Bjerrum length

Dear lammps users,

I have read Mark Steven’s paper about polyelectrolyte modeling. At there, he set the bjerrum length for the coulomb interaction. Up to my knowledge, setting up a proper dielectric constant is the same as setting up the bjerrum length. For example, if the bjerrum length is 7.1 A, then I should set up the dielectric constant about 78. Am I correct?

If I am wrong, please let me know and give me a hand to figure it out.

With my best regards

CCing Mark, who can answer.


Basically you have it correct. The Bjerrum length is not an LAMMPS input, the dielectric constant is. For the coarse-grained simulations, the LJ units are used and the dielectric constant is not 78 then.

Basically find out what the Bjerrum length is in LJ units for your system and the dielectric follows from that and the value of kT


Dear Dr. Mark Stevens,

It is my honor to get your reply, sir. Can I ask one more question? In the case of using a real unit for the coarse-grained model, is it fine for me to set proper dielectric constant matching the Bjerrum length? For example, is it correct setting the dielectric constant around 80 for the lammps input if the Bjerrum length is 7.1 A?

With my best respect

2021년 4월 30일 (금) 오전 3:47, Stevens, Mark <[email protected]>님이 작성: