linesearch alpha is zero

Dear All,

I am minimizing the energy of a nanowire using the “minimize” command. The commands are below.

min_modify line quadratic
minimize 1e-14 1.0e-16 10000000000 10000000000000000

## mimimization status###

Minimization stats:
Stopping criterion = linesearch alpha is zero
Energy initial, next-to-last, final =
-1159874.48481 -1162533.53611 -1162533.53611
Force two-norm initial, final = 169.753 0.00269875
Force max component initial, final = 1.34532 0.000371144
Final line search alpha, max atom move = 0.000976562 3.62446e-07
Iterations, force evaluations = 1936 3890

Stopping criterion for minimization is “linesearch alpha is zero”. Is this criterion a reliable check for minimization?
Though the energy difference between the next-to-last and final step is zero, why not the system stopped by ‘etol’ criterion?



The minimize doc page discusses this in detail.