14. Wavefunctions in density functional theory are approximated by a summation of plane waves. Atypical plane wave cutoff (i.e. the highest energy planewave used in the approximation) is on theorder of about 20 Hartrees.(a) Compare the wavelength of the highest-energy planewave to the length scale of typicalinteratomic distances.(b) Interpret your answer to (a) and explain briefly how the sum of plane waves is able to produce anapproximation of the wavefunction.

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Answered: 14. Wavefunctions in density functional…

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