Dear Jay,

After about one minute on Google I found this:

http://www.sklogwiki.org/SklogWiki/index.php/9-3_Lennard-Jones_potential

Hope this helps you!

Sincerely,

Christer H. Ersland.

Dear Jay,

After about one minute on Google I found this:

http://www.sklogwiki.org/SklogWiki/index.php/9-3_Lennard-Jones_potential

Hope this helps you!

Sincerely,

Christer H. Ersland.

Dear Christer,

Thank you for your link. The reason why I want to find out how the LJ9-3 model in LAMMPS manual is derived because in the manual it says:

LJ93=epsilon((2/15)(sigma/r)^9-(sigma/r)^6)

But if you derive LJ93 directly from LJ12-6 via integration method (also proven by the link you sent), LJ93 should be:

LJ93=(2/3)*pi*epsilon*sigma^3*((2/15)(sigma/r)^9-(sigma/r)^6)

Comparing the two equations, you realise that the terms (2/3), pi, rho, and sigma^3 are all missing. Therefore I am wondering when I input the value of epsilon in LAMMPS, do I only consider the value of epsilon purely, or do I assume:

epsilon (in LAMMPS LJ93 model) = (2/3)*pi*epsilon*sigma^3

Best regards,

Jay

Let's see what Mark says about this.

Steve