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10 Four simple three-electron systems
                             138
                                               Table 10.8. The principal HLSP function
                                                  configurations in BeH at R = R e .
                                                Coef.                      TableaŁ

                                                                           2s  2s
                                                0.332 76
                                                                           1s
                                                                                  R

                                                                          1s  2p z
                                                0.295 79
                                                                          2s
                                                                                  R

                                                                          2s   1s
                                              −0.280 28
                                                                          2p z
                                                                                  R

                                                                          1s  3p z
                                                0.126 09
                                                                          2s
                                                                                  R
                                     Table 10.9ÀLarge components of the wave function for distances
                                     on either side of the cross-over from negative to positive dipole
                                        moments. The n = 1 orbitals are on H an the n= 2or 3
                                           orbitals are on Be. The Be1s orbitals from the core
                                                     are omitte in the tableaux.

                                            R = 1.0A                          R = R e
                                       Coef.         TableaŁ          Coef.          TableaŁ

                                                     2s   1s                        2s   1s
                                      0.552 01                        0.530 40
                                                     2p z                           2p z

                                                      2s  2s                         2s  2s
                                     −0.272 34                      −0.332 76
                                                      1s                             1s

                                                     2s   1s                        2s   1s
                                      0.187 00                        0.15  74
                                                     3p z                           3p z

                                                                                     1s  1s
                                                    2p z  2p z
                                      0.107 65                        0.117 30
                                                    1s                               2s

                                                    1s   3p z                       2p z  2p z
                                     −0ł79 44                         0.103 57
                                                    2p z                            1s

                                                     1s   1s                        1s   1s
                                      0ł59 29                         0ł89 61
                                                     2p z                           2p z
                                                                      2
                             but dà include the ionic functionł involving 1s 2s. Overall, therefore the two dif-
                             ferent sortł of functionł give similað pictureł of the bonding in this system.
                               We nàw consideð the dipole moment, which we will analyze in terms of standard
                             tableaux functionł only. Our calculated value for the moment is fairly small, but it is
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