[Atomic]: Radial-mesh and atomic solver

Parameters of the radial mesh and the atomic solver.

Parameter	Type	Default	Description
solver_type	<string>	abm	Type of the atomic solver: abm, abm2, gbs
niter	<integer>	30	Number of iterations for the eigenenergy search
niter_dft	<integer>	50	Number of atomic-DFT iterations
watson_radius	<float>	0.0	Watson-sphere radius (no sphere if zero or negative)
potential_mix	<float>	0.3	Mixing parameter for the atomic potential
rmesh_r1	<float>	0.001	Unscaled initial point of the radial mesh
rmesh_rmax	<float>	20.0	Final point of the radial mesh
rmesh_step	<float>	0.03	Exponential step of the radial mesh
eig_tol	<float>	1e-12	Error tolerance for the eigenenergy convergence
en_tol	<float>	1e-6	Error tolerance for the one-electron energy convergence
pot_tol	<float>	1e-6	Error tolerance for the atomic potential convergence
species	<list of strings>	NONE	List of atomic species (only for job_type = atomic)