exercises:2015_ethz_mmm:mo_ethene
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exercises:2015_ethz_mmm:mo_ethene [2015/02/06 17:49] – external edit 127.0.0.1 | exercises:2015_ethz_mmm:mo_ethene [2015/04/17 15:33] – oschuett | ||
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- | ====== Molecular orbitals of Ethene ====== | + | ======= Molecular orbitals of Ethene |
In this exercise, you will perform an electronic structure calculation to obtain the ethene molecular orbitals (MOs). If performed correctly, your calculations will produce a list of occupied and non occupied MOs and a series of *.cube files, that allow the visualization of the oribital with VMD. | In this exercise, you will perform an electronic structure calculation to obtain the ethene molecular orbitals (MOs). If performed correctly, your calculations will produce a list of occupied and non occupied MOs and a series of *.cube files, that allow the visualization of the oribital with VMD. | ||
- | ==== 1. Step ==== | + | ===== 1. Step: Run the calculation ===== |
Run a calculation with the following (commented) input file. \\ | Run a calculation with the following (commented) input file. \\ | ||
Note that the file contains explicit basis sets and potential for all-electron calculations. An explanation of the basis set formats is given here: [[basis_sets|Basis Sets]] | Note that the file contains explicit basis sets and potential for all-electron calculations. An explanation of the basis set formats is given here: [[basis_sets|Basis Sets]] | ||
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&DFT | &DFT | ||
- | & | + | & |
- | NHOMO 5 ! Number of HOMOs to be printed (count starts from the highest occupied orbital. -1 = all). Here 5. | + | NHOMO 5 |
- | NLUMO 5 ! Number of LUMOs to be printed (count starts from the lowest unoccupied orbital). Here 5. | + | NLUMO 5 |
&END MO_CUBES | &END MO_CUBES | ||
+ | & | ||
+ | NLUMO 5 | ||
+ | &END | ||
&END PRINT | &END PRINT | ||
& | & | ||
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- | ==== 2. Step ==== | + | ===== 2. Step ===== |
- | If the calculation was performed correctly, a list of ALL the occupied MOs and 3 (as specified in the input) unoccupied MOs eigenvalues are printed in the output. \\ | + | If the calculation was performed correctly, a number |
- | The ethene band gap (energy difference between HOMO and LUMO) is also printed. | + | |
< | < | ||
- | + | $ ls *.pdos *.cube | |
- | | + | ethene-k1-1.pdos |
- | ***** ** *** *** ** | + | ethene-k2-1.pdos |
- | | + | |
- | ***** ** ** ** ** | + | |
- | **** ** ******* | + | |
- | + | ||
- | ..... | + | |
- | Eigenvalues of the occupied subspace spin 1 | + | |
- | | + | |
- | list of eigenvalues | + | |
- | .... | + | |
- | + | ||
- | Lowest Eigenvalues of the unoccupied subspace spin 1 | + | |
- | ----------------------------------------------------- | + | |
- | list of eigenvalues | + | |
- | ..... | + | |
- | + | ||
- | HOMO - LUMO gap [eV] : | + | |
- | ...... | + | |
- | + | ||
- | + | ||
- | **** **** ****** | + | |
- | ***** ** *** *** ** | + | |
- | | + | |
- | ***** ** ** ** ** | + | |
- | **** ** ******* | + | |
</ | </ | ||
- | <note important> | + | First have a look at the *.pdos files. PDOS stands for Projected Density of States. These files list the energies and occupation of the MOs. Furthermore, they show how the MOs are compose from basis-functions of different atoms (one pdos-file for each atomic kind) and angular momentum (s,p,d). Hence, these numbers always sum up to 1.0. |
+ | ===== 3. Step ===== | ||
- | ==== 3. Step ==== | + | Now look at the *.cube files. |
+ | Each cube-file contains the electronic density of one MO mapped onto a regular 3D-grid. Not all MOs were written to a cube-file, this is controlled by the PRINT_MO section. Their filenames tell you to which MO a cube-file belongs. For example '' | ||
- | In addition | + | Use VMD to visualize |
- | The number of cubes strictly depends on what you have specified in the PRINT_MO section. No extra files are generated (while in the output a default list of all the occupied MOs eigenvalues is anyway produced.) | + | |
- | ∗.cube files report the structure of a given MO and can be visualized with VMD: | + | |
- | + | | |
- | | + | - In this second representation set **Drawing Method=Isosurfaces** and **Draw=Wireframe** |
- | | + | |
- | * To visualize the MO structure in VMD: | + | |
- | | + | |
- | | + | |
- | | + | |
- | | + | |
What you get should look similar to this: | What you get should look similar to this: | ||
{{ ethene_pi_orbital.png |}} | {{ ethene_pi_orbital.png |}} | ||
- | ==== Questions ==== | ||
- | |||
- | - Quickly sketch the energy distribution for the occupied MOs and the five unoccupied MOs. \\ | ||
- | - By using VMD, identify the shape and energy of the π and π* orbitals. | ||
- | |||
+ | ===== Questions ===== | ||
+ | - Quickly sketch the energy distribution of the MOs. | ||
+ | - What's the energy of the HOMO, LUMO, and the band-gap? | ||
+ | - Use VMD to identify the shape and energy of the $\pi$ and $\pi^*$ orbitals. | ||
| | ||
- |
exercises/2015_ethz_mmm/mo_ethene.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1