:orphan:
Converging atoms
================
DIRAC presently does not perform an open-shell Hartree--Fock in a strict sense,
rather an average-of-configuration calculation, which amounts to the
optimization of the average energy of a set of configurations (or determinants)
generated from the specification of a given number of open shells and their
electron occupations. In the case of atoms, a convergence problem can occur when
the inner open-shell orbitals are more stable than outer "closed" shell.
From DIRAC21 onwards, we have atomic supersymmetry and can specify the occupation number of each :math:`\kappa` value. by using the keyword :ref:`SCF_.KPSELE`.
As examples of such calculations, we consider the Nb and Np atoms.
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Example 1: Nb [Kr]4d\ :sup:`4`\ 5s\ :sup:`1`\
-----------------------------------------------------
::
**DIRAC
.WAVE FUNCTION
.ANALYZE
**HAMILTONIAN
.X2C
**INTEGRALS
*READIN
.UNCONTRACT
**WAVE FUNCTION
.SCF
*SCF
.CLOSED SHELL
18 18
.OPEN SHELL
2
4/10,0
1/2,0
.KPSELE
5
-1 1 -2 2 -3
8 6 12 4 6
0 0 0 4 6
2 0 0 0 0
**ANALYZE
.MULPOP
*MULPOP
.VECPOP
1..oo
1..oo
**MOLECULE
*BASIS
.DEFAULT
dyall.2zp
*END OF
----------------------------------------------------------
Example 2: Np [Rn]5f\ :sup:`4`\6d\ :sup:`1`\7s\ :sup:`2`\
----------------------------------------------------------
::
**DIRAC
.WAVE FUNCTION
.ANALYZE
**HAMILTONIAN
.X2C
**INTEGRALS
*READIN
.UNCONTRACT
**WAVE FUNCTION
.SCF
*SCF
.CLOSED SHELL
44 44
.OPEN SHELL
2
4/0,14
1/10,0
.KPSELE
7
-1 1 -2 2 -3 3 -4
14 10 20 12 18 6 8
0 0 0 0 0 6 8
0 0 0 4 6 0 0
**ANALYZE
.MULPOP
*MULPOP
.VECPOP
1..oo
1..oo
**MOLECULE
*BASIS
.DEFAULT
dyall.2zp
*END OF