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

Optimized Structure

 0.000211   -2.968615    0.000632
-4.756537    1.245164   -0.223717
-1.225855    0.373813   -1.421418
-2.439580   -0.689901    1.977915
-1.595176    3.015012    1.213944
 1.225936    0.373940    1.421968
 2.438948   -0.689855   -1.977896
 1.594716    3.015094   -1.213820
-3.779934   -2.460329   -1.046608
 4.756413    1.245571    0.223046
 3.780859   -2.459895    1.045953

                    Distance matrix (angstroms):
                    1          2          3          4          5
     1  Ca   0.000000
     2  Ca   6.358688   0.000000
     3  Ca   3.833704   3.828766   0.000000
     4  Ca   3.880047   3.736301   3.762987   0.000000
     5  Ca   6.310402   3.897876   3.749329   3.875958   0.000000
     6  Ca   3.833440   6.265564   3.754480   3.857051   3.870040
     7  Ca   3.880046   7.654831   3.856402   6.280802   6.339404
     8  Ca   6.310477   6.667186   3.869766   6.339535   4.008672
     9  Ca   3.955321   3.919385   3.833557   3.752159   6.313686
    10  Ca   6.358481   9.523435   6.265122   7.655582   6.667495
    11  Ca   3.955349   9.392904   6.259792   6.534164   7.674932
                    6          7          8          9         10
     6  Ca   0.000000
     7  Ca   3.763261   0.000000
     8  Ca   3.749544   3.875976   0.000000
     9  Ca   6.259846   6.532715   7.674313   0.000000
    10  Ca   3.829024   3.736397   3.897707   9.392280   0.000000
    11  Ca   3.834011   3.751990   6.313581   7.845023   3.919102
                   11
    11  Ca   0.000000

SCF Done:  E(RB+HF-PW91) =  -7452.90374378 au

E(11 atoms of Calcium) = -7452.607611 au

Binding Energy = 8.0582 ev (0.7326 ev/atom)