opt

This option controls the geometry optimization details.

num_steps

Value	An integer
Default	1000

The maximum number of geometry optimization steps.

epsilon

Value	A real number
Default	1.E-5

The l-BFGS convergence condition. If the ratio of gradient norm to coordinate norm is less than epsilon, then the optimization is assumed to be converged. This only works if l-BFGS is used.

grad_cov

Value	A real number
Default	1.E-3

The gradient convergence threshold. When grad_cov and dr_cov are both met, the optimized structure will be set to be converged.

dr_cov

Value	A real number
Default	1.E-3

The displacement convergence threshold. When grad_cov and dr_cov are both met, the optimized structure will be set to be converged.

fix_atoms

Value	Atom range
Default	None

Assign the atoms that are fixed during geometry optimization. For example:

opt
  fix_atom 2 5-9 23 26
end

The atoms 2,5,6,7,8,9,23,26 will be fixed during geometry optimization.

fix_bond

Value	2 integers
Default	None

Assign the bond that are fixed during geometry optimization. For example:

opt
  fix_bond 1 4
  fix_bond 2 6
end

The bonds (1,4) and (2,6) will be fixed during geometry optimization.

fix_angle

Value	3 integers
Default	None

Assign the angle that are fixed during geometry optimization. For example:

opt
  fix_angle 1 4 5
  fix_angle 2 6 7
end

The angles (1, 4, 5) and (2, 6, 7) will be fixed during geometry optimization.

fix_torsion

Value	4 integers
Default	None

Assign the torsion that are fixed during geometry optimization. For example:

opt
  fix_torsion 1 4 5 9
  fix_torsion 2 6 7 12
end

The torsions (1, 4, 5, 9) and (2, 6, 7, 12) will be fixed during geometry optimization.