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

Optimized Structure

    1         20             0        0.000000    2.750368    1.148099
    2         20             0       -1.933846   -1.933846   -2.110663
    3         20             0        2.750368    0.000000    1.148099
    4         20             0       -2.750368    0.000000    1.148099
    5         20             0        0.000000   -2.750368    1.148099
    6         20             0        1.933846    1.933846   -2.110663
    7         20             0        1.933846   -1.933846   -2.110663
    8         20             0       -1.933846    1.933846   -2.110663
    9         20             0        0.000000    0.000000    3.850259

                    Distance matrix (angstroms):
                    1          2          3          4          5
     1  Ca   0.000000
     2  Ca   6.025044   0.000000
     3  Ca   3.889608   6.025044   0.000000
     4  Ca   3.889608   3.876338   5.500737   0.000000
     5  Ca   5.500737   3.876338   3.889608   3.889608   0.000000
     6  Ca   3.876338   5.469742   3.876338   6.025044   6.025044
     7  Ca   6.025044   3.867692   3.876338   6.025044   3.876338
     8  Ca   3.876338   3.867692   6.025044   3.876338   6.025044
     9  Ca   3.855671   6.558362   3.855671   3.855671   3.855671
                    6          7          8          9
     6  Ca   0.000000
     7  Ca   3.867692   0.000000
     8  Ca   3.867692   5.469742   0.000000
     9  Ca   6.558362   6.558362   6.558362   0.000000

SCF Done:  E(RB+HF-PW91) =  -6097.79646532 au

E(9 atoms of Calcium) = -6097.588045 au

Binding Energy = 5.67145 ev (0.63016 ev/atom)