Step 4: Calculate the vibrational frequencies of ethane

Now we will set up and run the frequencies calculation. It is important to start with the optimized structure, so make sure you did import the optimized coordinates (the last step of the previous instructions).

Select the 'Frequencies' preset

Note that selecting the Frequencies preset increases the integration accuracy. This is required to get accurate results. However, the calculation will take much longer:

Select 'Run' from the 'File' menu
Click 'OK' to save over the current results
Wait for the calculation to finish (about 4 minutes, depending on your hardware)