(Solution) - a For CH2O run HF 3 21G geometry optimization and vibrational frequency calculations -(2025 Original AI-Free Solution)

Paper Details

(a) For CH2O, run HF/3-21G geometry optimization and vibrational-frequency calculations to obtain the predicted geometry, dipole moment, and harmonic vibrational wavenumbers. Verify that all vibrational wavenumbers are real.
(b) Repeat (a) using a HF/6-31G* calculation. Multiply the HF/6-31G* harmonic wavenumbers by the 0.895 scale factor and compare the results with the fundamental wavenumbers listed in the CCCBDB.
(c) Using a program such as the WebMO Demo or Spartan Student that can show animations of each normal mode, view the modes and sketch each CH2O normal mode using arrows to show atomic motions. For modes that involve out-of-plane vibrations, it is helpful to rotate the model as it vibrates. Also, have the program draw the predicted infrared spectrum.
(d) From the predicted IR normal-mode intensities, which mode has the strongest absorption and which the weakest?
(e) Each normal mode can be classified according to its symmetry species. Use the results of part (c) to give the symmetry species of each normal mode.