5.3.6. band_minimizer.pccg

eminus.band_minimizer.pccg(scf, W, Nit, cost=scf_step_occ, grad=get_grad_occ, condition=check_convergence, betat=3e-5, cgform=1, precondition=True)

Preconditioned conjugate-gradient minimization algorithm for a fixed Hamiltonian.

Parameters:

• scf – SCF object.

• W – Expansion coefficients of unconstrained wave functions in reciprocal space.

• Nit – Maximum number of SCF steps.

Keyword Arguments:

• cost – Function that will run every SCF step.

• grad – Function that calculates the respective gradient.

• condition – Function to check and log the convergence condition.

• betat – Step size.

• cgform – Conjugate gradient form.

• precondition – Whether to use a preconditioner.

Returns:

Band energies per SCF cycle and optimized expansion coefficients.