Topic

Ionization energy

About: Ionization energy is a(n) research topic. Over the lifetime, 7998 publication(s) have been published within this topic receiving 207461 citation(s). The topic is also known as: electron binding energy & ionisation energy.

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Journal ArticleDOI: 10.1063/1.475855
Abstract: This paper presents an evaluation of the performance of time-dependent density-functional response theory (TD-DFRT) for the calculation of high-lying bound electronic excitation energies of molecules. TD-DFRT excitation energies are reported for a large number of states for each of four molecules: N2, CO, CH2O, and C2H4. In contrast to the good results obtained for low-lying states within the time-dependent local density approximation (TDLDA), there is a marked deterioration of the results for high-lying bound states. This is manifested as a collapse of the states above the TDLDA ionization threshold, which is at ??HOMOLDA (the negative of the highest occupied molecular orbital energy in the LDA). The ??HOMOLDA is much lower than the true ionization potential because the LDA exchange-correlation potential has the wrong asymptotic behavior. For this reason, the excitation energies were also calculated using the asymptotically correct potential of van Leeuwen and Baerends (LB94) in the self-consistent field step. This was found to correct the collapse of the high-lying states that was observed with the LDA. Nevertheless, further improvement of the functional is desirable. For low-lying states the asymptotic behavior of the exchange-correlation potential is not critical and the LDA potential does remarkably well. We propose criteria delineating for which states the TDLDA can be expected to be used without serious impact from the incorrect asymptotic behavior of the LDA potential

Topics: , Bound state (53%), Ionization (51%) ...read more

4,187 Citations

Journal ArticleDOI: 10.1063/1.460205
Abstract: The Gaussian‐2 theoretical procedure (G2 theory), based on a b i n i t i o molecular orbital theory, for calculation of molecular energies (atomization energies, ionization potentials,electron affinities, and proton affinities) of compounds containing first‐ (Li–F) and second‐row atoms (Na–Cl) is presented. This new theoretical procedure adds three features to G1 theory [J. Chem. Phys. 9 0, 5622 (1989)] including a correction for nonadditivity of diffuse‐s p and 2d f basis set extensions, a basis set extension containing a third d function on nonhydrogen and a second p function on hydrogen atoms, and a modification of the higher level correction. G2 theory is a significant improvement over G1 theory because it eliminates a number of deficiencies present in G1 theory. Of particular importance is the improvement in atomization energies of ionic molecules such as LiF and hydrides such as C2H6, NH3, N2H4, H2O2, and CH3SH. The average absolute deviation from experiment of atomization energies of 39 first‐row compounds is reduced from 1.42 to 0.92 kcal/mol. In addition, G2 theory gives improved performance for hypervalent species and electron affinities of second‐row species (the average deviation from experiment of electron affinities of second‐row species is reduced from 1.94 to 1.08 kcal/mol). Finally, G2 atomization energies for another 43 molecules, not previously studied with G1 theory, many of which have uncertain experimental data, are presented and differences with experiment are assessed.

Topics: , , Diatomic molecule (50%) ...read more

3,153 Citations

Journal Article
Maciej Lewenstein1, Ph. Balcou, Misha Ivanov2, Anne L'Huillier3  +1 moreInstitutions (3)
01 Mar 1994-Physical Review A
Abstract: We present a simple, analytic, and fully quantum theory of high-harmonic generation by low-frequency laser fields. The theory recovers the classical interpretation of Kulander et al. in Proceedings of the SILAP III Works hop, edited by B. Piraux (Plenum, New York, 1993) and Corkum [Phys. Rev. Lett. 71, 1994 (1993)] and clearly explains why the single-atom harmonic-generation spectra fall off at an energy approximately equal to the ionization energy plus about three times the oscillation energy of a free electron in the field. The theory is valid for arbitrary atomic potentials and can be generalized to describe laser fields of arbitrary ellipticity and spectrum. We discuss the role of atomic dipole matrix elements, electron rescattering processes, and of depletion of the ground state. We present the exact quantum-mechanical formula for the harmonic cutoff that differs from the phenomenological law Ip+3.17Up, where Ip is the atomic ionization potential and Up is the ponderomotive energy, due to the account for quantum tunneling and diffusion effects.

Topics: Ponderomotive energy (63%), ,  ...read more

2,710 Citations

Journal Article
Abstract: We report here an approach for predicting charge distributions in molecules for use in molecular dynamics simulations. The input data are experimental atomic ionization potentials, electron affinities, and atomic radii. An atomic chemical potential is constructed by using these quantities plus shielded electrostatic interactions between all charges. Requiring equal chemical potentials leads to equilibrium charges that depend upon geometry. This charge equilibration (QEq) approach leads to charges in excellent agreement with experimental dipole moments and with the atomic charges obtained from the electrostatic potentials of accurate ab initio calculations. QEq can be used to predict charges for any polymer, ceramic, semiconductor, or biological system, allowing extension of molecular dynamics studies to broad classes of new systems. The charges depend upon environment and change during molecular dynamics calculations. We indicate how this approach can also be used to predict infrared intensities, dielectric constants, and other charge-related properties.

Topics: Molecular dynamics (55%), Electrostatics (54%), Ionization energy (53%) ...read more

2,560 Citations

Journal Article
Gregory H. Wannier1Institutions (1)
01 Aug 1937-Physical Review
Abstract: In this article, a method is devised to study the energy spectrum for an excited electron configuration in an ideal crystal. The configuration studied consists of a single excited electron taken out of a full band of $N$ electrons. The multiplicity of the state is ${N}^{2}$. It is shown that because of the Coulomb attraction between the electron and its hole ${N}^{\frac{8}{5}}$ states are split off from the bottom of the excited Bloch band; for these states the electron cannot escape its hole completely. The analogy of these levels to the spectrum of an atom or molecule is worked out quantitatively. The bottom of the Bloch band appears as "ionization potential" and the Bloch band itself as the continuum above this threshold energy.

Topics: Excited state (57%), Ionization energy (54%), Electron (51%) ...read more

1,530 Citations

Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20224
2021145
2020154
2019196
2018167
2017193

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Topic's top 5 most impactful authors

Wen Bih Tzeng

55 papers, 716 citations

Joseph Vincent Ortiz

29 papers, 1.1K citations

Majdi Hochlaf

28 papers, 340 citations

John M. Dyke

28 papers, 639 citations

Patrick Hemberger

25 papers, 302 citations

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