Home work Physical and Theoretical Chemistry IV

- Molecular Spectroscopy -

Discussion  Fr 13.01.2006 at 12:15,  HR30.1



  Home work 9.  Molecular Symmetry. Character Tables.

Exercise 1:   

a)   To which irreducible representations belong  s,  px, py, and pz oxygen atomic orbitals in H2O molecule?  Are these representations degenerate, or non-degenerate?

b)  Consider the above problem for the  s,  px, py, and pz nitrogen atomic orbitals in NH3 molecule.

Exercise 2:

           a)  Consider the ammonia molecule. Prove that the combination of  hydrogen atomic orbitals:

                s1 = Ya(1s) + Yb(1s)  + Yc(1s) 

               belongs  to the totally symmetric A1 representation. 

            b)  For the same molecule prove that the combinations of  atomic orbitals

                 s2 = -Ya(1s) + 1/2 [ Yb(1s)  + Yc(1s)]     and      s3 = Yb(1s)  - Yc(1s)

                 belong to the doubly degenerate E representation.

Hint:  Show that under operations of the ammonia molecule symmetry group the wavefunctions s2 and s3 are transformed as linear combinations of each other.

Exercise 3:

            a)  Consider the wavefunction obtained from two hydrogen atom orbitals in water molecule: 

                   hs = ha(1s) + hb(1s).

                Which representation this wavefunction belongs to? Which oxygen atom atomic orbitals can be used in combination  with  the wavefunction hfor building binding and anti-binding molecular orbitals?  

           

           

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