     CAPUT, ver. 0.22 .
`
     The presented programs demonstrate ab initio calculations
of some simple systems with taking into account configuration
interaction (CI).
     The most part of the source text was taken from the program
ORBIT8 written by D.A.Zhogolev (Prepr. No. 7 of Inst. Phys. Chem.,
Acad. Sci. UkrSSR, Kiev). The fragment of configuration
interaction was written with the use of the principles presented
in the book of S.Huzinaga. A contracted nodeless gaussian basis
for simplest atoms was designed independently by fitting the
analytical orbitals of the hydrogen atom.
     The presented programs allocate the array of two-electron
integrals via XMS memory specification and, as a result, they
can work under Turbo Pascal compiler.
`
     The program H_VOZB.PAS demonstrates the quality of the
basis functions: for H atom with basis 1s, 2sp, 3spd, 4s,
we obtain, as it is expected:
  2 sublevels with energy 1/2*1    ~= -0.4993 (1s);
  8         -//-          1/2*1/4  ~= -0.1247 (2s, 2p);
 18         -//-          1/2*1/9  ~= -0.0553 (3s, 3p, 3d);
  2         -//-          1/2*1/16 ~= -0.0304 (4s);
  2         -//-                       0.0058 (due to 6 3d-functions).

     The program H_MI.PAS demonstrates how essential is CI
for description of ion H-. Without CI, the energy of its ground
state is -0.4796 a.u., i.e., it is unstable (for H atom, energy
is -0.5 a.u.). With CI, the energy becomes equal to -0.5098 a.u.,
i.e., the ion becomes stable (as it is in experiment).
`
     The program H2_PAS demonstrate "rational" dissociation limit
for the H2 molecule when taking CI into account (without CI,
the dissociation limit is pathological).
`
     The program H_NE.PAS demonstrate calculation of several lowest
electronic levels of atoms from H to Ne (for Ne, the result is not
satisfactory).
`
Energy, eV   Term   No. of    Comment
Expe. Calc.  SL_J  sublevels
`
0.00  0.00  3P_012    9       lowest term of s2p2 config.;
                              LS-splitting=0.005 eV is not calculated
1.26  1.27   1D_2     5       s2p2 config.
2.68  3.16   1S_0     1       s2p2 config.
4.18  4.89   5S_2     5       lowest term of sp3 configuration
`
     (The experimental energies were taken from:
Radtsig A.A., Smirnow B.M., Parameters of atoms and atomic ions: Reference
Book [in Russian], Moscow, Energoatomizdat, 1986 (樣 .., ୮ ..,
ࠬ ⮬  ⮬ , ., ࣮⮬, 1986)).
`
