1. Double-click the Materials Science icon
   • (No icon? See Starting Maestro)

Figure 2-1. Change Working Directory option.

2. Go to File > Change Working Directory
3. Find your directory, and click Choose
4. Pre-generated input files are included for running jobs. Download the zip file here: schrodinger.com/sites/default/files/s3/release/current/Tutorials/zip/dipole_moment.zip
5. After downloading the zip file, unzip the contents in your Working Directory for ease of access throughout the tutorial

Figure 2-2. Save Project panel.

6. Go to File > Save Project As
7. Change the File name to dipole_moment_tutorial, click Save
   • The project is now named dipole_moment_tutorial.prj

Figure 2-3. Import structure file.

8. Go to File > Import Structures
9. Navigate to where you downloaded the provided tutorial files, choose input_molecules.maegz and click Open

Figure 2-4. The three structure entries.

The imported entries are now available in the entry list. The entry group contains three entries: the first is a single iridium complex and the other two are multi-component systems.

Figure 3-1. The Ir_molecule entry in the workspace.

1. With Ir_molecule includedthe entry is represented in the Workspace, the circle in the In column is blue in the workspacethe 3D display area in the center of the main window, where molecular structures are displayed and selected(1) the atoms are chosen in the Workspace. These atoms are referred to as "the selection" or "the atom selection". Workspace operations are performed on the selected atoms. (2) The entry is chosen in the Entry List (and Project Table) and the row for the entry is highlighted. Project operations are performed on all selected entries in the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion, go to Tasks > Materials > Quantum Mechanics > Molecular Quantum Mechanics > QM Multistage Workflow
   • The QM Multistage Workflow panel opens
   • As an alternative, the Jaguar - Single Point Energy panel would suffice

Figure 3-2. The QM Multistage Workflow panel.

2. Ensure that Use structures from shows Project Table (1 selected entry)
3. Change the basis set to LACVP**
   • Of course, other functionals and basis sets are also appropriate. This level of theory will match the options when calculating the transition dipole moment for multi-component systems in the following sections.
4. Go to the Theory Tab

Figure 3-3. Selecting the TDDFT theory options.

5. Check the Excited state (TDDFT) box and change the drop-down menu to Tamm-Dancoff approximation
   • The Tamm-Dancoff approximation (TDA) is favored to address the low orbital overlap and triplet instability problems in TDDFT, providing a better description of singlet and triplet excitations
6. Increase the Number of excited states to 3
   • The default number is acceptable, but increasing to 3 will match the options when calculating the transition dipole moment for the multi-component systems in the subsequent sections
7. Change the Job name to Ir_molecule_dipole
8. Adjust the job settings () as needed
   • This job requires a CPU host and can be completed in about 5 minutes on 4 processors
9. Click Run

Figure 3-4. The Ir_molecule_dipole output.

Once the calculation is complete, the molecule is automatically incorporated in the workspacethe 3D display area in the center of the main window, where molecular structures are displayed and is available in the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion

10. Includethe entry is represented in the Workspace, the circle in the In column is blue the output from the calculation in the workspacethe 3D display area in the center of the main window, where molecular structures are displayed

Figure 3-5. The Visualize Transition Dipole Moment panel.

Now we can visualize the transition dipole moment

11. Go to Tasks > Materials > Quantum Mechanics > Tools > Visualize Transition Dipole Moment
    • The Visualize Transition Dipole Moment panel opens
    • The results should automatically populate into the panel, but if not, click Browse and navigate to the Ir_molecule.out file
12. Under Show, check all three boxes to visualize the transition dipole moment vector

Figure 3-6. Viewing the transition dipole moment rod (hydrogen atoms hidden for ease of visualization).

The transition dipole moments are shown as rods indicating the orientation of the transition dipole moment. The length of the rod is significant and indicates a stronger oscillator, but note that the location is simply centered on the molecule’s center of mass. The location of the rod does not imply where the excitation occurs in the molecule.

You can display the transition dipole moments for each of the transitions in a given molecule, and assign a color to distinguish them. In the Figure, the lowest energy transition dipole is shown in green.

13. Close the Visualize Transition Dipole Moment panel

Figure 4-1. The disordered multi-component system in the Workspace.

1. In the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion includethe entry is represented in the Workspace, the circle in the In column is blue and select(1) the atoms are chosen in the Workspace. These atoms are referred to as "the selection" or "the atom selection". Workspace operations are performed on the selected atoms. (2) The entry is chosen in the Entry List (and Project Table) and the row for the entry is highlighted. Project operations are performed on all selected entries the disordered_Ir_system entry

This system is composed of three different molecules on top of a SiO₂ layer. The components are color-coded for easier viewing. The green molecules are Ir(ppy)₃ complexes and are the molecules of interest in this example. See the References section (“Solution-processed multilayer small-molecule light-emitting devices with high efficiency white-light emission”) for more information about this system

2. Go to Tasks > Materials > Quantum Mechanics > Optoelectronic Film Properties > Optoelectronic Film Properties
   • The Optoelectronic Film Properties panel opens

Figure 4-2. The Transition Moment Order Parameter panel.

3. Ensure that Use structures from shows Workspace (included entry)
4. Check the Transition dipole moment order parameter option
5. Change the Compute order parameter for these molecules to be the Ir complex, (Ir(ppy)₃ ): C₃₃H₂₄IrN₃ #:67
   • There are 67 Ir(ppy)₃ molecules in this system
6. Change the Job name to tdm_disordered_Ir_system
7. Adjust the job settings () as needed
   • This job requires a CPU host and can be completed in about 10 minutes on 4 processors
8. Click Run

Figure 4-3. The calculated transition dipole moment output structure.

When the job is complete, the results are automatically incorporated in the workspacethe 3D display area in the center of the main window, where molecular structures are displayed and are available in the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion

9. Select(1) the atoms are chosen in the Workspace. These atoms are referred to as "the selection" or "the atom selection". Workspace operations are performed on the selected atoms. (2) The entry is chosen in the Entry List (and Project Table) and the row for the entry is highlighted. Project operations are performed on all selected entries and includethe entry is represented in the Workspace, the circle in the In column is blue the output in the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion and workspacethe 3D display area in the center of the main window, where molecular structures are displayed, respectively.
   • Note that the structure will resemble the input structure, but now also contains the data from the Optoelectronic Film Properties calculation
10. Use the WAM (workflow action menu) button () to open the Optoelectronic Film Properties Viewer
    • Alternatively, access the panel via Tasks > Materials > Quantum Mechanics > Optoelectronic Film Properties > Optoelectronic Film Properties Viewer
• The Optoelectronic Film Properties Viewer panel opens

Figure 4-4. The Transition Moment Order Viewer panel of the lowest excited state (here, S₁).

11. If you opened the panel with the WAM button, the results should automatically populate into the viewer. If not click Load from Workspace and load tdm_disordered_Ir_system.csv
12. Click Bins to change the number of bins shown
    • We can include more bins in order to see the transition dipole moment angle distribution over a wider range (e.g. 0-180°)

Figure 4-5. Altering the number of bins.

13. Click Define bin edges
14. Start the bins at 0 with a Stepsize of 10 and 18 as the Number of bins
    • This will span the bin size from 0-180° in 10° increments
15. Click OK to close the panel

Figure 4-6. Viewing the transition dipole moment angle distribution of the lowest excited state (here, S₁).

Out of the 67 iridium molecules, the plot shows the count of transition dipole moments at various angles

16. Click Show in Workspace to view the transition dipole moment vectors

Note that the calculated transition dipole moment is for the lowest excited state, whether that state is singlet (S₁, as for current case study) or triplet (T₁) when calculating the TDM order parameter and plotting the distribution.

Figure 4-7. Defining the molecules of interest.

Keep the panel open and return to the workspace.

Since we calculated the transition dipole moment for the Ir complexes, let's hide the other two molecules (red and blue) for easier viewing of the vectors. We can undisplay molecules multiple ways, one way is described in the following steps.

17. Click Define in the top menu

Figure 4-8. Selecting the red and blue molecules.

18. Go to the Molecule tab
19. Select Molecule type
20. Select M2 - 241 and M3 - 241
21. Click Add
    • These molecules will now be in the ASL box below
22. Click OK to close the panel

Figure 4-9. Hiding the red and blue molecules.

All the red and blue molecules are selected in the workspace

23. Go to the Style palette in the toolbar
24. Click the closed eye to Undisplay Selected Atoms

Figure 4-10. The Ir complexes with their transition dipole moment vectors.

After hiding, only the Ir complexes (colored green) are shown. We can see the transition dipole moment vectors. They are represented by blue and green arrows. Feel free to zoom in on your structure for easier viewing.

The blue vectors represent a transition dipole moment between a 45-135° angle (which is ideal in this application) otherwise the arrow is green. We see vectors pointing in all directions due to the disordered nature of the system. Even though the system was equilibrated prior to this calculation, the disordered nature is expected given that the system was built using the disordered system builder tool.

25. Close the Optoelectronics Film Properties panel

Figure 5-1. Calculating the transition dipole moment for the ordered Ir system

Following similar steps to Section 4, let’s calculate the transition dipole moment for an ordered system which was built using the Molecular Deposition panel. This system contains 26 Ir complexes on an SiO₂ layer. Once again, we are interested in calculating the transition dipole moment for the Ir complexes.

1. In the entry list, includethe entry is represented in the Workspace, the circle in the In column is blue and select(1) the atoms are chosen in the Workspace. These atoms are referred to as "the selection" or "the atom selection". Workspace operations are performed on the selected atoms. (2) The entry is chosen in the Entry List (and Project Table) and the row for the entry is highlighted. Project operations are performed on all selected entries the ordered_Ir_system entry
   • See the References section for more information about this system
2. Go to Tasks > Materials > Quantum Mechanics > Optoelectronic Film Properties > Optoelectronic Film Properties
   • The Optoelectronic Film Properties panel opens
3. Ensure that Use structures from shows Workspace (included entry)
4. Change the Compute order parameter for these molecules to the Ir complexes: C₂₇H₂₂₃IrN₂O₂ #:26
5. Change the Job name to tdm_ordered_Ir_system
6. Adjust the job settings () as needed
   • This job requires a CPU host and can be completed in about 10 minutes on 4 processors
7. Click Run

Figure 5-2. The calculated transition dipole moment output structure.

When the job is complete, the results are automatically incorporated in the workspacethe 3D display area in the center of the main window, where molecular structures are displayed and are available in the entry lista simplified view of the Project Table that allows you to perform basic operations such as selection and inclusion

8. Select(1) the atoms are chosen in the Workspace. These atoms are referred to as "the selection" or "the atom selection". Workspace operations are performed on the selected atoms. (2) The entry is chosen in the Entry List (and Project Table) and the row for the entry is highlighted. Project operations are performed on all selected entries and includethe entry is represented in the Workspace, the circle in the In column is blue the output
   • Note that the structure will resemble the input structure, but now also contains the data from the Optoelectronic Film Properties calculation

Figure 5-3. Defining the molecules of interest.

This time, let’s hide the host molecules and show only the Ir complexes before we plot the TDM vectors:

9. Click Define in the top menu

Figure 5-4. Selecting the molecules to undisplay.

10. Go to the Molecule tab
11. Select Molecular weight
12. Enter 484.606
13. Click Add
    • There are many ways to select the Ir complexes using ASL, here we arbitrarily choose to define the complexes by molecular weight for easy identification
14. Click OK to close the panel.
15. Go to Style in the toolbar
16. Click the closed eye to Undisplay Selected Atoms

Figure 5-5. The Ir complexes in the system.

Only the 27 Ir complexes remain visible on the SiO₂ layer

17. Use the WAM (workflow action menu) button () to open the Optoelectronic Film Properties Viewer
    • Alternatively, access the panel via Tasks > Materials > Quantum Mechanics > Optoelectronic Film Properties > Optoelectronic Film Properties Viewer
• The Optoelectronic Film Properties Viewer panel opens

Figure 5-6. Viewing the transition dipole moment angle distribution.

18. If you opened the panel with the WAM button, the results should automatically populate into the viewer. If not click Load from Workspace and load tdm_ordered_Ir_system.csv
19. Change the number of Bins so the plot displays the Transition Moment Angle from 0-180° in 10° increments
20. Click Show in Workspace to view the transition dipole moment vectors

This structure was built in a more ordered fashion using the Molecular Deposition panel, compared to the structure in Section 4. We see that there are fewer transition dipole moment angles at very low and very high angles.

Figure 5-7. The Ir complexes with their transition dipole moment vectors.

In this case, we see much more order in the transition dipole moment vectors. This agrees with expectation based on the transition dipole moment angle distribution plot.

21. Close the Optoelectronic Film Properties Viewer panel

Figure 5-8. Viewing the TDM Order Parameter.

Lastly, we can view the TDM Order Parameter values in the Project Table.

22. Open the Project Table
23. In the Property Tree on the right, expand the All menu
24. Expand the Material Science menu
25. Expand the Primary drop down menu
26. Add TDM Order Parameter from the Primary menu
27. Scroll to the right in the table to see the TDP Order Parameter

Note that in addition to the TDM Order Parameter, properties are also printed for TDM S1 Order Parameter, TDM S2 Order Parameter, and TDM S3 Order Parameter.