# How to use COSMOSS?
Within the COSMOSS directroy, you will see 'COSMOSS.mlapp'. Double click on it or type in 'COSMOSS' in the working space will bring up the main GUI interface:


Select a structure model by clicking the 'Constructing structural model' button on the top left 'Build Model Structure' panel. You should see another GUI shows up. Take the two coupled oscillators model for example, you should see the GUI like this:


Adjusting the parameters on the model_GUI then click the 'Generate' button to pass the 'Structure Data' back to the main GUI (COSMOSS) for spectral simulations. You can also visualize the constructed molecule by clicking the 'Draw' button on the model_GUI to confirm the desired structure.


After generating the molecule one can simulate spectrum by clicking the corresponding spectral type on the button row of the Main_GUI. The figure below shows example FTIR, SFG, 2DIR, and 2DSFG spectrum of the above constructed carboxylic acid dimer. Note that the FTIR and the SFG provides the same information as the diagonal slice of the corresponding 2D spectrum. With 2D spectrum, one have extra information form the second dimension, including the off-diagonal peaks (mode coupling), off-diagonal line width (possibility to separate homogeneous and inhomogeneous line with on the diagonal), and many more subtle features that may need further spectral analysis to extra information.


For spectral analysis, the bottom right 'Analysis tool' panel provides buttons or different tool_GUIs.
:::info
More information about the analysis tools will coming soon...
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###### tags: `tutorials` `COSMOSS`