Excited States by Calculation and Simulated Electronic Spectra · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Reading a computed spectrum

Science · Chemistry · ages 23-24
Name ______________________   Date ____________

  1. One excited state lists several orbital contributions of different weights. How do you name the orbitals of the transition?

    • Use the contribution with the largest weight
    • Blend every contribution equally
    • Use the contribution with the smallest weight

  2. A computed list gives an energy and an oscillator strength for each excited state. What does the oscillator strength control in the predicted spectrum?

    • Where the band appears
    • How tall the band is
    • How many atoms the dye has

  3. Common functionals usually place charge transfer excitation energies too low.

    Circle one:   True   False

  4. An output lists HOMO minus 1 to LUMO at 0.1, HOMO to LUMO at 0.8, and HOMO to LUMO plus 1 at 0.1. How do you assign the transition?

    • A blend with no leading part
    • HOMO to LUMO
    • HOMO minus 1 to LUMO plus 1

  5. Two computed states share one broadening width, and one has the larger oscillator strength. How do their predicted bands compare?

    • The stronger one sits at higher energy
    • The stronger one splits in two
    • The stronger one rises taller

  6. A computed band matches a measured band, so no further check of the difference is needed.

    Circle one:   True   False

  7. A computed band sits at 2.9 electron volts and the measured band at 2.5 electron volts. By how many electron volts is the computed band too high? Type the number.

    Answer: ______________

  8. A dye calculation puts an excitation far too low, and the orbitals show charge moving across the molecule. What likely causes the error?

    • The functional mishandles long range charge transfer
    • The sticks were broadened too little
    • The spectrum lacks measured bands
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Reading a computed spectrum W1-mt_DsZ3wfCRkX-s1

  1. Use the contribution with the largest weight · The largest weight names it, and the small ones are ignored.
  2. How tall the band is · Energy sets the position, while strength sets the height.
  3. True · Charge transfer states are the classic case that comes out too low.
  4. HOMO to LUMO · The 0.8 weight dominates, so you name it HOMO to LUMO.
  5. The stronger one rises taller · Equal width with larger strength gives a taller band at its own position.
  6. False · You still assign the shift to solvent, vibrational, or method causes.
  7. 0.4 · Subtract the two positions: 2.9 minus 2.5 is 0.4.
  8. The functional mishandles long range charge transfer · Distant charge shift with too low energy marks the exchange approximation failure.
Worksheet · LightMySky