If the square modulus of the gradient (composed of forces and stress) falls below relax_accuracy, the relaxation stops.
Default: relax_accuracy 0.01
Don't choose it to be less then 0.001, since this is generally close to the accuracy with which the forces and stress is computed.
To avoid runaway jobs, the variable relax_max_iter determines the maximum number of relaxation steps to be performed. The statement
relax_max_iter 10
instructs the code to do at most 10 relaxation steps.
Default: relax_max_iter 0