A
 b i
 n
 i
 t
 i
 o relativistic effective potentials with spin–orbit operators. III. Rb through Xe

LaJohn, L.A.; Christiansen, P. A.; Ross, Ronald J.; Atashroo, T.; Ermler, Walter C.

doi:10.1063/1.453069

Cited by 770 publications

(410 citation statements)

References 17 publications

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“…For the main group elements In, Sn and Sb, pseudopotentials have been published by several authors [8][9][10][11][12][13][14]. Instead of the adjustment to orbital energies and orbital densities [8][9][10][11][12][13], the pseudopotentials used in this work [14] are fitted to experimental ionization and excitation energies of one-valence electron atoms [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of spectroscopic properties of some indium, tin and antimony compounds

et al. 1989

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Section: Introductionmentioning

confidence: 99%

Comparative study of spectroscopic properties of some indium, tin and antimony compounds

et al. 1989

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“…The relativistic effective core potential of LaJohn et al 58 was used, which replaces the 1s, 2s, 2p, 3s, 3p, and 3d electrons of Rb. The basis set used was built on their 5s,5p set ͑contracted to 4s,3p͒.…”

Section: B Ab Initio Calculationsmentioning

confidence: 99%

The structure of alkali halide dimers: A critical test of ionic models and new ab initio results

Törring

Biermann

Hoeft

et al. 1996

The Journal of Chemical Physics

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The structure of alkali halide dimers: A critical test of ionic models and new ab initio results. T. Torring, S. Biermann, J. Hoeft, R. Mawhorter, R. J. Cave, and C. Szemenyei, J. Chem. Phys. 104, 8032 (1996) In semiempirical ionic models a number of adjustable parameters have to be fitted to experimental data of either monomer molecules or crystals. This leads to strong correlations between these constants and prevents a unique test and a clear physical interpretation of the fit parameters. Moreover, it is not clear whether these constants remain unchanged when the model is applied to dimers or larger clusters. It is shown that these correlations can be substantially reduced when reliable information about dimers is available from experiments or ab initio calculations. Starting with Dunham coefficients of the monomer potential determined from microwave measurements, we have calculated the monomer to dimer bond expansion and the bond angle without any additional adjustable parameter. Assuming that the overlap repulsion between nearest neighbors remains unchanged, the bond expansion is mainly determined by the simple Coulomb repulsion between equally charged ions and depends only very little on the effective ion polarizabilities. Deviation of the bond angle from 90°sensitively tests the difference of effective polarizabilities of the two ions. A comparison with previously available data and new ab initio MP2 results presented here for the heavy-atom containing dimers shows that bond angles can be modeled reasonably well with SeitzRuffa corrected Pauling polarizabilities while calculated bond expansions are much too long. This shows that changes of the overlap repulsion term must be considered for reliable predictions of the structure of dimers and larger clusters.

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“…23,24 The CRENBL ECP basis 25,26 is used for atoms larger than Kr. All (TD-)DFT geometry optimizations and subsequent frequency calculations are carried out using the Q-Chem 4.2 program package, 27 employing a EulerMaclaurin -Lebedev product quadrature grid comprising 75 radial points and 302 angular points per radial point, with an SCF convergence threshold of 10 −8 and geometry optimization thresholds decreased by an order of magnitude from their default values.…”

Section: Methodsmentioning

confidence: 99%

Quadratic Corrections to Harmonic Vibrational Frequencies Outperform Linear Models

Sibaev

Crittenden

2015

J. Phys. Chem. A

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Simulating accurate infrared spectra is a longstanding problem in computational quantum chemistry. Linearly scaling harmonic frequencies to better match experimental data is a popular way of approximating anharmonic effects while simultaneously attempting to account for deficiencies in ab initio method and/or basis set. As this approach is empirical, it is also non-variational and unbounded, so it is important to separate and quantify errors as robustly as possible. Eliminating the confounding factor of methodological incompleteness enables us to explore the intrinsic accuracy of the scaling approach alone. We find that single-coefficient linear scaling methods systematically overcorrect low frequencies, while generally undercorrecting higher frequencies. A two-parameter polynomial model gives significantly better predictions without systematic bias in any spectral region, while a single-parameter quadratic scaling model is parameterized to minimize overcorrection errors while only slightly decreasing predictive power.

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A b i n i t i o relativistic effective potentials with spin–orbit operators. III. Rb through Xe

Cited by 770 publications

References 17 publications

Comparative study of spectroscopic properties of some indium, tin and antimony compounds

Comparative study of spectroscopic properties of some indium, tin and antimony compounds

The structure of alkali halide dimers: A critical test of ionic models and new ab initio results

Quadratic Corrections to Harmonic Vibrational Frequencies Outperform Linear Models

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