Dear Steve,

There was some problem when I tried to producing a EAM potential file written in *funcfl* format using the spline parameters provided in the paper " EAM potential for magnesium from quantum mechanical forces " *( Modelling Simul. Mater. Sci. Eng. 4 (1996) 293-303. )* . Though I am contacting with the author , still I am in great need of your assistance .

Sorry that I can’t afford you PDF version of that paper . Here are part of those parameters and their instruction :

The spline parameters for the pair potential function are in the form of a **spline function** which is calculated from

e(x)=y(i)+b(i)(r-r(i))+c(i)(r-r(i))**2+d(i)(r-r(i))**3

where r(i) is the spline knot position, y(i) is the function value at the knot, and c(i) and d(i) are the derivative coeffcients that construct the spline function . All of them are given in a table as follow ,

r(i) y(i) b(i) c(i) d(i)

2.100000 3.072927 -8.860487 9.330483 -3.454020

2.280000 1.247677 -4.447802 6.429107 -3.893891

2.620000 0.325584 -1.426411 2.457338 -1.737102

…

6.580000 -0.001100 0.013000 0.015200 -0.385400

6.700000 0.00 0.00 0.00 0.00

So as the way Lammps read *funcfl* format I apprehend , I set them as follow :

Nr = 3000 , dr = 1.533 E-3 , cutoff = 6.7 ( here , cutoff - dr * Nr = 2.1 ang. )

But the system couldn’t even get equilibrium . That is , without analytic formula I can’t get datas when r < 2.1 angstroms if Lammps really need to know that .

Could you please give me some instructions to produce a EAM potential file only with optimized spline parameters starting around 2.1 angstroms just like mentioned above .

If this is impossible , please allow me to put forward another question :

Is it wrong to model a single-element metal using a *setfl* format alloy potential file with an " .eam.alloy " suffix which contians two or more elements , because the cutoff and " atomic density " would be different ?

Heartfelt thanks and best regards !

Sincerely

Xiaozhi Tang