How to use only one interaction from an EAM alloy force filed file

Hi everyone,

I want to use an EAM force field file named ‘AuPd.eam.alloy’, but I only need to use that file for Au-Au interaction. My input data also only includes Au atoms. The pair style in input file is ‘eam/fs’ and I don’t know how to define the pair_coeff directly even though I have tried several commands from Lammps documentation. I tried ‘1 1 AuPd.eam.alloy Au Au’ , ‘* * AuPd.eam.alloy Au Pd’ and ‘* * AuPd.eam.alloy Au Au’, all of those didn’t work.

May I ask for any suggestions on this problem? Any response is appreciated.

Best,

Kevin

this is definitely wrong. the documentation clearly says that you must use pair_coeff * * ...

this would only be correct, if you create a box with two atom types, and you don’t use the second atom type.

same as above, only that both atom types may be used.

As stated in the documentation, the number of elements following the potential file must be the same as the number of atom types. The solution should therefore be obvious.

Hi Prof. Axel Kohlmeyer,

Thank you for kind reply. I have added one more atom type in data file, and used the command
** ‘* * AuPd.eam.alloy Au Pd’. **
**However, the simulation cannot work with the error: **
ERROR on proc 0: Not a valid floating-point number: ‘fcc’ (src/OPENMP/pair_eam_fs_omp.cpp:192).

And here is my input file initialization:

******Initialization

units metal
boundary p p p
atom_style full

neigh_modify delay 5 every 5 check yes

variable Q world 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

pair_style eam/fs

***read_data

read_data Au147.data

variable t world 300.0 320.0 340.0 360.0 380.0 400.0 420.0 440.0 460.0 480.0 500.0 520.0 540.0 560.0 580.0 600.0 620.0 640.0 660.0 680.0 700.0 720.0 740.0 760.0 780.0 800.0 820.0 840.0 860.0 880.0 900.0 920.0 924.0 928.0 932.0 936.0 940.0 944.0 948.0 952.0 956.0 958.0 960.0 980.0 1000.0 1020.0 1040.0 1060.0 1080.0 1100.0 1120.0 1140.0 1160.0 1180.0 1200.0 1220.0 1240.0

pair_coeff * * AuPd.eam.alloy Au Pd

May I ask for the possible reason for this error? I got the EAM force file from others and here are several lines of that potential:

Pd-Au potential from Marchal et al., J. Phys. Chem. C 117, 21810 (2013)
parameter rho_m from Table 1 of the paper is taken as parameter gamma [see Eq. (5) of Supplemental Information of the original paper]
generated 2015-05-13 22:13:09.571054
2 Au Pd
5000 0.006 5000 0.0012 6.000000
79 196.97 4.0782 fcc
0 -0.00188405514165723709 -0.00376725616019002452 -0.00564960305559814024 -0.00753109582788247245
-0.00941173447704257704 -0.011291519003078232 -0.0131704494059896593 -0.0150485256857770811 -0.0169257478424396091
-0.0188021158759783535 -0.0206776297863926484 -0.0225522895736827156 -0.0244260952378485552 -0.0262990467788903892.

Thank you and I appreciate your response.

You are using the wrong pair style. This is a potential file for pair style eam/alloy, but you are using pair style eam/fs. Those potential files are not compatible and thus the error.

It works. sorry for my carelessness and thanks so much for the reply.