Word Pronunciation & Dictionary

koopmans' theorem

Word Rarity Very rare

Frequency: Zipf frequency 1.66 in modern English

Syllables: koop-man-s' the-o-rem
IPA

28

Scrabble Score

15

Letters

5

Syllables

11

Unique Chars

Meaning

name

A theory stating that, in closed-shell Hartree-Fock theory, the first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital (HOMO).

Example Sentences

"There exists another approach to correct the DFT and its related Kohn-Sham Hamiltonian: the Koopmans’ theorem¹¹⁻²². The original Koopmans’ theorem only states that in Hartree-Fock, the first ionization energy is equal to the highest occupied orbital energy if the wave function relaxations are ignored. In the literature¹¹⁻²¹, the terminology “Koopmans’ theorem” was used to indicate the straight-line condition (SLC) of the total energy E(n) as a function of the continuous number of electrons n between two integer points²³."

Etymology

Named after Dutch-American mathematician Tjalling Koopmans (1910–1985), who published this result in 1934.

Questions

What does koopmans' theorem mean?: A theory stating that, in closed-shell Hartree-Fock theory, the first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital (HOMO).
Where does koopmans' theorem come from?: Named after Dutch-American mathematician Tjalling Koopmans (1910–1985), who published this result in 1934.

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