Provide initial guess for SCF step

[jeanwsr]

dh/pyscf/dh/rdfdh.py

Lines 50 to 56 in 2ac67ac

	def energy_elec_nc(mf: RDFDH, mo_coeff=None, h1e=None, vhf=None, **_):
	if mo_coeff is None:
	if mf.mf_s.e_tot == 0:
	mf.run_scf()
	if mf.xc_n is None: # if bDH-like functional, just return SCF energy
	return mf.mf_s.e_tot - mf.mf_s.energy_nuc(), None
	mo_coeff = mf.mf_s.mo_coeff

Since kwargs are not passed to run_scf, so currently it's not possible to pass initial guess, is it?

So I'm wondering which solution is preferred: allow users passing dm0 in as kwargs, or encourage users running mf.mf_s manually after DH initialized?

An even more flexible implementation could be allow initializing upon mf_or_mol, like

https://github.com/pyscf/pyscf/blob/0785373fb5f11105bc41743565cf4b7e13464c92/pyscf/mcscf/casci.py#L779

[jeanwsr]

After some experiment I found mf.mf_s.kernel(dm0=dm) is not recomended since it will leave mf.mo_coeff undefined.
Running mf.run_scf(dm0=dm); mf.run() seems reasonable.

[ajz34]

For this implementation, it is actually encouraged for users running mf.mf_s manually after DH initialized. The attribute mf.mf_s can be arbitrarily changed by user for their demands.
It is not a good way for API design, only scripting available.