Using Gaussian98
b3pw91/6-311g(d) scf=direct fopt

Optimized Structure

    1         20             0        0.000000    3.041026    1.622805
    2         20             0       -2.150330   -2.150330   -1.622805
    3         20             0        3.041026    0.000000    1.622805
    4         20             0       -3.041026    0.000000    1.622805
    5         20             0        0.000000   -3.041026    1.622805
    6         20             0        2.150330    2.150330   -1.622805
    7         20             0        2.150330   -2.150330   -1.622805
    8         20             0       -2.150330    2.150330   -1.622805
    9         20             0        0.000000    0.000000    0.000000

                    Distance matrix (angstroms):
                    1          2          3          4          5
     1  Ca   0.000000
     2  Ca   6.489074   0.000000
     3  Ca   4.300660   6.489074   0.000000
     4  Ca   4.300660   3.993900   6.082052   0.000000
     5  Ca   6.082052   3.993900   4.300660   4.300660   0.000000
     6  Ca   3.993900   6.082052   3.993900   6.489074   6.489074
     7  Ca   6.489074   4.300660   3.993900   6.489074   3.993900
     8  Ca   3.993900   4.300660   6.489074   3.993900   6.489074
     9  Ca   3.446931   3.446931   3.446931   3.446931   3.446931
                    6          7          8          9
     6  Ca   0.000000
     7  Ca   4.300660   0.000000
     8  Ca   4.300660   6.082052   0.000000
     9  Ca   3.446931   3.446931   3.446931   0.000000

SCF Done:  E(RB+HF-PW91) =  -6097.79996113 au

E(9 atoms of Calcium) = -6097.588045 au

Binding Energy = 5.7666 ev (0.6407 ev/atom)