## The H3 cyclic cluster

In this section you will calculate the wavefunction of a H3 cluster by loading a CRYSTAL input file: H3_cyclic.inp

Exercise 1: Start DLVisualize and run a CRYSTAL calculation:

Questions:

1. What are the H-H distances?
   Compare with the H-H distance in the previous systems.
2. Did you use the same hamiltonian/method adopted in the calculation of the hydrogen atom and molecule?
3. What is the energy of the H3 cluster in Hartree?
   In the output, the energy is given in atomic unit (Hartree).
   Convert the energy in eV and in J.
   Compare this energy with the energy of the linear H3 cluster Which conclusion can be drawn?
4. What are the energies of the molecular orbitals?
   Hints: Look for the string "FINAL EIGENVALUES (A.U.)" at end of the output.
   The energies are given in atomic unit (Hartree). Convert in eV and in J.
   Compare the energies of the molecular orbitals of both H3 clusters.

Optional questions::

1. Is it possible to identify a non-bonding molecular orbital?
   Compare the eigenvalues with the energy of the occupied atomic orbital of hydrogen atom.

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