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## Useful hints

- The program should be easy to use provided you can start a calculation for a specific system. You should not encounter any serious problems when the system contains atoms from the first two rows of the Periodic Table. Then even the rough hydrogenic estimates of the orbitals should prove adequate and after the initial couple of dozen of iterations a smooth convergence should set in.

  If, however, a system contains more than 15-20 electrons the initial estimates of the orbitals have to be good enough to avoid divergences. Then, you have to choose the parameters of the hydrogenic orbitals carefully or perform the finite basis set calculations using the Gaussian94 to provide the initialization data for orbitals.

- Do not start calculations on too dense a grid. For example, the grid is sufficient to check the quality of the initial data for the Ne system.

- At the very beginning set the maximum number of scf iterations to something between 20 and 50 and/or impose crude convergence criteria for the orbital energy and normalization.

- Choose small values of the relaxation parameters ( ) to avoid divergence in the first few dozens of iterations. Later on the parameters should be increased to a desired (optimum) values (see the Ne example).

  The dependence of the optimum value of the relaxation parameter on the grid size is illustrated by the following table:

  50 50 | 1.89
  100 100 | 1.94
  159 100 | 1.96
  300 300 | 1.98

  Now it is possible to set to its near-optimal value by using a semiempirical formula (B.Sobczak MSc Thesis, Torun 2002); see the description of the label above.

  Optimum values of the orbital relaxation parameter are somewhat smaller and are not directly related to the grid size. In most cases choosing should lead to fairly good convergence rates.

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