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

Optimized Structure

 1.655599    1.705683   -2.450563
 4.089717    0.000498    0.000824
-1.657188    2.938053   -0.529718
 1.657265   -2.448864   -1.706407
 1.653513    2.454064    1.704179
-4.088283   -0.000935    0.000051
 1.656504   -1.705667    2.452371
-0.001221   -0.000216    0.002783
-1.655180   -0.528293   -2.938960
-1.657049    0.526829    2.940610
-1.653677   -2.941152    0.524829

                    Distance matrix (angstroms):
                    1          2          3          4          5
     1  Ca   0.000000
     2  Ca   3.852517   0.000000
     3  Ca   4.022802   6.475926   0.000000
     4  Ca   4.220667   3.851082   6.433434   0.000000
     5  Ca   4.221606   3.854412   4.023094   5.972505   0.000000
     6  Ca   6.473811   8.178000   3.850783   6.474232   6.472966
     7  Ca   5.972945   3.852481   6.437200   4.224663   4.226483
     8  Ca   3.416731   4.090939   3.414558   3.415814   3.414145
     9  Ca   4.023734   6.475013   4.221375   4.022446   6.434333
    10  Ca   6.436465   6.476472   4.225775   6.436940   4.025272
    11  Ca   6.434077   6.474138   5.973034   4.022822   6.437137
                    6          7          8          9         10
     6  Ca   0.000000
     7  Ca   6.474763   0.000000
     8  Ca   4.087063   3.414249   0.000000
     9  Ca   3.851738   6.435830   3.415889   0.000000
    10  Ca   3.851794   4.025177   3.413264   5.973494   0.000000
    11  Ca   3.853255   4.024815   3.413539   4.221342   4.226453
                   11
    11  Ca   0.000000

SCF Done:  E(RB+HF-PW91) =  -7452.91138467 au

E(11 atoms of Calcium) = -7452.607611 au

Binding Energy = 8.2662 ev (0.7515 ev/atom)