The H3 linear cluster
In this section you will calculate the wavefunction of a H3 cluster
by loading a CRYSTAL input file: H3_linear.inp
Exercise 1: Start DLVisualize and
run a CRYSTAL calculation:
Calculate->CRYSTAL->Run SCF Input file
Click on Browse
The Job List panel will open automatically and look something like this;
Select the job and the status line should
report "Job has completed" - like this;
Click on Recover Files.
A model of H3 should have appeared in the DLV 3DView window.
A second window will open displaying the output from the CRYSTAL calculation
It should look something like H3_linear.out
Take some time to read through the output in order to answer
to the following questions.
- What are the H-H distances?
Compare with the H-H distance in the H2 molecule.
- Did you use the same hamiltonian/method adopted in the calculation of
the hydrogen atom and molecule?
- What is the energy of the H3 cluster
In the output, the energy is given in atomic unit (Hartree).
Convert the energy in eV and in J.
Compare this energy with the exact energy of three isolated hydrogen atoms.
Which conclusion can be drawn?
- 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 H3 with H2.
- Is it possible to identify a non-bonding molecular orbital?
Compare the eigenvalues with the energy of the occupied atomic orbital
of hydrogen atom.