Abstract:
Calculations are performed on the \S <:Jd ground states of
d ' +
the H and HC) molecules using a basis set of non-integral
~ ~ I
elliptical orbitals. Different variational wavefunctions constructed
i- for H~ involved one parameter to three par~~eter variation.
In order to l"'educe the ntunber of parameters in most commonly
0-
used basis orbitals set, the importance of the term (,+~)
Y\ over the term ;u 'Where n is a variational pararneter and the value
of cr may be given by boundary condition or cusp condition is
outlined in Chapters II and III. It is found that the two parameter
-+ <J""'
wavefunction for H~ including the ternl (~+~) , a- given by the
bound~ condition, gives lower variational energies than any wavefunction
published to date for small and moderate internuclear
separations.
c;.
In order to find out the importance of the term (I +~ )
Y\
over ;U for the two electron problem, the variational energy is
computed for the H~ molecule from unrestricted two parameter
closed shell wavefunctions including the term U+ft)<J w11ere the
value of rr is obtained from the boundary condition in one case
and from the cusp condition in the second case.
In order to take into account in-out correlation partially,
open shell calculation for the ground state of the hydrogen molecule
for R =1.4 (equilibrium internuclear separation) is perfonaed.
The results are excellent.
