Formaldehyde Frequencies in Acetonitrile

we will consider the vibrational frequencies of formaldehyde in acetonitrile, using the Onsager SCRF model and the SCIPCM model. Acetonitrile is a highly polar solvent, with an e value of 35.9. In order to predict the vibrational frequencies, we ll first need to optimize the structure for formaldehyde in this medium. Thus, we ll be running these jobs  

A molecular volume calculation to estimate Oq for the Onsager model. 

An SCRF geometry optimization, beginning at the optimized gas phase structure, for each model. 

An SCRF frequency calculation at the two SCRF optimized structures. Note that frequency calculations must be run as a separate job step for SCRF calculations (Opt Freq does not do what might be expected). 

The volume calculation results in a cavity radius of 3.65. The acetonitrile solution produces only subtle changes in the molecule s structure. The only significant change is a decrease of 0.3-0.4° in the O-C-H bond angle. 

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