Different results in different systems

Dear All,

I am minimizing the energy of a nanowire using minimize “command”.
I ran simulations in Linux machine and Mac. I am getting different force and energy values at the end of the run. The stopping criterion is also different for the two machines

here are the different results

In both machines, I used the same tolerance values

minimize 1e-14 1e-16 10000000000 10000000000000000

Linux

Minimization stats:
Stopping criterion = linesearch alpha is zero
Energy initial, next-to-last, final =
-48779.708133 -49541.5982041 -49541.5982041
Force two-norm initial, final = 82.8119 0.00671866
Force max component initial, final = 1.61637 0.000683582
Final line search alpha, max atom move = 0.000244141 1.6689e-07
Iterations, force evaluations = 2195 4371

Mac

Minimization stats:
Stopping criterion = energy tolerance
Energy initial, next-to-last, final =
-48779.708133 -49544.6353335 -49544.6353335
Force two-norm initial, final = 82.8119 0.000229873
Force max component initial, final = 1.61637 7.12061e-05
Final line search alpha, max atom move = 1 7.12061e-05
Iterations, force evaluations = 5057 10113

Moreover, If I use the below tolerance values

minimize 0 0 10000000000 10000000000000000

Linux gives

Minimization stats:
Stopping criterion = linesearch alpha is zero
Energy initial, next-to-last, final =
-48779.708133 -49541.5982041 -49541.5982041
Force two-norm initial, final = 82.8119 0.00671866
Force max component initial, final = 1.61637 0.000683582
Final line search alpha, max atom move = 0.000244141 1.6689e-07
Iterations, force evaluations = 2195 4371

Mac

Minimization does not stop. probably it stops after reaching specified no. of iterations, which is very large in this case.

Could anyone help me

Thanks
Sivashankar

That’s just the way different machines work, especially
when you are dealing with tiny precision values.

Steve