Excitation energies and UV/Vis spectrum of ethene¶

Select calculations options¶

To set up the calculation of the excitation spectrum:

Adjust the title to something like ‘Ethene excitations’

Select the ‘Single Point’ preset

Use the panel bar Properties → Excitations (UV/Vis), CD command to go to the Excitations panel

For the ‘Type of excitations’ option, Select ‘Singlet and Triplet’

For the tutorial this set up is fine, normally you would also need to select an XC potential that gives better results, for example SAOP.

Run the calculation¶

Now everything is ready to actually run ADF. Before running we will save the current input in a different file (though this is not really required):

Select File → Save As...

Enter a filename (ethene-exci) and click ‘Save’

Select File → Run

Wait for the calculation to finish

Logfile: ADFtail¶

The logfile shows you that the calculation has finished, and that indeed the excitation code has been running:

Select SCM → Logfile

Energy levels: level diagram and DOS¶

Select SCM → Levels

In this level diagram you can see that the HOMO and LUMO consist mainly of carbon p orbitals. It is also easy to see what orbitals the hydrogens take part in.

Note that the carbon and hydrogen stacks show all carbon and hydrogen atoms at once: they show the fragment type. ADFlevels can also show the individual fragments but when using atomic fragments you will get too many fragments. In this particular case symmetry is used, and since there is only one symmetry unique carbon atom and only one symmetry unique hydrogen atom you still would see only one stack per atom type.

Select SCM → DOS

In the ADFdos window:

View → Add Graph

Select one hydrogen atom

In these plots you can see that the partial DOS for the hydrogen atoms have no contribution to the HOMO. By right clicking on an atom you can also show partial DOS graphs with contribution from selected atoms and selected L-values only.

Excitation spectrum: ADFspectra¶

Select SCM → Spectra

ADFspectra will start and show the calculated excitation spectrum.

In the window below the spectrum you will find a table with information. You can get more information by selecting one of the entries (or click on the peak in the spectrum):

In the table select the Singlet-Singlet1B3.u peak

The composition of the excitation in terms of orbital transitions is listed on the right side. In many cases you can visualize relevant orbitals or NTOs with ADFview by clicking on them in the window on the right. The clickable items are visually marked.

Click on the the first major contribution line (with the highlighted orbitals)

Close the two windows showing the orbitals using File → Close in both windows

Orbitals, orbital selection panel: ADFview¶

We will now use ADFview to examine the orbitals. Not just one, but have a look at many of them. To do that ADFview has an ‘orbital selection’ panel.

Select SCM → View

Select Properties → HOMO

Click on the field selector pull-down in the control bar for the HOMO (reading SCF_B1.u 1: ...),

select Orbitals (occupied)

In the ‘Select Occupied Orbital’ window you can select the orbital that you want to see. Note that the currently visible orbital is highlighted using a dark green background.

Click on all of the orbitals in the window, one by one, and observe the orbitals

Click again on them

When you click the first time on an orbital, its values need to be calculated and then the orbital is shown. When you click for a second time on an orbital in the list, it has already been calculated (indicated by the light green background color). And thus it shows immediately.

The Orbital select window allows you to reorder the orbitals by clicking on the headers of the columns. Thus you can sort by Symmetry, Spin, etc. Clicking again on a header reverts the sort order.

Click on ‘Symmetry’ in the ‘Select Occupied Orbital’ window

Close ADFview: File → Close

Transition density: ADFview¶

You can use ADFview to view orbitals etc, but also to have a look at the transition density.

Select Add → Isosurface: Double (+/-)

In the field pull-down menu (in the control line for the double isosurface) you will find an entry ‘Transition Density’, and if you select it an orbital select box will shown with all available transition densities:

In this case lets select the transition density that belongs to the biggest peak: the Singlet-Singlet 1B3u excitation:

Click on the TransDens_SS_B3.u_Fitdensity_1 field

Change the iso value to 0.003

Rotate the molecule a little

The resolution is rather coarse, you can use interpolation to get a better picture.

Fields → Interpolated

Select the Transition Density → TransDens_SS_B3.u_Fitdensity_1 field in the I-1 line

In the Isosurface: Double line, change the field to I-1 (in the Other category in the field selector)

ADF Output¶

Using the output browser you can find all details about your excitation calculation. Use the menu to jump to the relevant part of output:

Select SCM → Output

Select Response Properties → All Singlet-Singlet Excitation Energies

KFBrowser¶

Most result of the calculation are saved to the KF result file (the .t21 file for an ADF calculation). You can inspect the contents of KF files using the KFBrowser. The KFBrowser is a very recent development, feedback and bug reports (there will be bugs...) are welcome!

The KFBrowser gets the raw data out of the result file, and presents a selection of that might be of interest for users. Over time more results will probably be added to newer versions of the KFBrowser.

It also gives access to all raw data in the result files. This feature is intended for developers only.

Select SCM → KFBrowser

In the KFBrowser window that appears:

Click on the arrow in front of Excitations

Click on the arrow in front of Energies (Hartree) (in the Excitations section)

If you click on the name of the property you can select it. Next you can copy it, and paste it for example in Excel:

Click on “Energies (Hartree)”

Copy (from the Edit menu or the usual shortcut)

Open Excel or some text editor

Paste

After pasting you should have your results nicely formatted in Excel or in some text document. Note that the values are tab-separated, so pasting into Excel will automatically put the data (energies) in cells.

In a similar way you can copy/paste other results. Or even all results:

In the KFBrowser window:

Edit → Select All

Edit → Copy

In the Excel or text editor window:

Paste

All results should be nicely formatted in your text document or spreadsheet:

Another feature of the KFBrowser is that it can show results in simple graphs:

Close the KFBrowser window

Open it again SCM → KFBrowser

Open the Charges section

Click on Mulliken (e)

Shift-click on MDC-Q (e)

Use the Graph → Selection As Graph command (or double click on the selection)

A window should appear that shows the selected results, charges in this case:

You can use the Graph style buttons to switch to different graph types (XY, Bars or Piechart).

Switch to the KFBrowser window

Open the Energies section

Select all energies (click on first, shift-click on last energy)

Double click on the selection

Finally two features that are intended for developers and expert users: the KFBrowser module can also show the raw data on the result file, and it can dump a KF file as a plain text file. To activate the expert mode, use the File → Expert Mode menu command. To save the contents of the result file as a text file using the File → Save As ASCII... command.

Closing the ADF-GUI modules¶

To close all modules for your excitations calculation at once, use the Close command from the SCM menu:

Select SCM → Quit

Close will close all open modules that have your current job loaded, except ADFjobs. The Close All command will close every ADF-GUI module, including ADFjobs:

Select SCM → Quit All

All ADF-GUI modules (and BAND-GUI modules if any) should be closed.