Powerful zero-point-energy converter – theory and experiment

<div> <div> <div>The precision and accuracy of theoretical vertical ionization potential calculations has improved to the point where more care is needed to make valid comparisons with experimental measurements then is currently the norm. Vertical ionization potentials (IPs) computed using the IP-EOMCCSD method are reported for 53 medium sized molecules (6 – 32 atoms) and compared with statistically evaluated experimental vertical IPs. Based on this comparison, theoretical IPs should be extrapolated to the complete basis set limit and corrected for vibrational zero-point energy, while for experimental data the intensity weighted mean band position should be reported as the vertical IP. Experimental data available for ethylene, E-2-butene, 2,5-dihydrofuran and pyrrole were re-analyzed and compared with zero-point energy corrected complete basis set theoretical estimates, yielding an average discrepancy of 0.05 eV between theory and experiment. In contrast the average of reported experimental vertical IPs (the comparison usually made) yielded an average discrepancy of 0.25 eV between theory and experiment for these molecules. Further analysis of the remaining molecules in the data set suggests that the majority of reported experimental vertical IPs are low because band asymmetries were not accounted for when assigning IP values. This leads to fortuitous good agreement between experiment and computations using the smaller aug-cc-pVDZ basis set without zero-point correction. In the case of 1,4-cyclohexadiene there is strong evidence for experimental uncertainty accounting for the discrepency between theory and experiment. The presented results provide a benchmark for evaluating both experimental and theoretical estimates of vertical ionization potentials for the 53 molecules studied. </div> </div> </div>

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Analysis and reporting recommendations for theoretical and experimental ionization potentials based on the study of 53 medium sized molecules using the IP-EOMCCSD method.

10.26434/chemrxiv.7448021 ◽

2019 ◽

Author(s):

Marissa Buzzanca ◽

Brandon Brummeyer ◽

Jonathan Gutow

Keyword(s):

Experimental Data ◽

Zero Point ◽

Ionization Potentials ◽

Basis Set ◽

Zero Point Energy ◽

Point Energy ◽

Complete Basis ◽

Complete Basis Set ◽

Vertical Ionization Potentials ◽

Theory And Experiment

<div> <div> <div>The precision and accuracy of theoretical vertical ionization potential calculations has improved to the point where more care is needed to make valid comparisons with experimental measurements then is currently the norm. Vertical ionization potentials (IPs) computed using the IP-EOMCCSD method are reported for 53 medium sized molecules (6 – 32 atoms) and compared with statistically evaluated experimental vertical IPs. Based on this comparison, theoretical IPs should be extrapolated to the complete basis set limit and corrected for vibrational zero-point energy, while for experimental data the intensity weighted mean band position should be reported as the vertical IP. Experimental data available for ethylene, E-2-butene, 2,5-dihydrofuran and pyrrole were re-analyzed and compared with zero-point energy corrected complete basis set theoretical estimates, yielding an average discrepancy of 0.05 eV between theory and experiment. In contrast the average of reported experimental vertical IPs (the comparison usually made) yielded an average discrepancy of 0.25 eV between theory and experiment for these molecules. Further analysis of the remaining molecules in the data set suggests that the majority of reported experimental vertical IPs are low because band asymmetries were not accounted for when assigning IP values. This leads to fortuitous good agreement between experiment and computations using the smaller aug-cc-pVDZ basis set without zero-point correction. In the case of 1,4-cyclohexadiene there is strong evidence for experimental uncertainty accounting for the discrepency between theory and experiment. The presented results provide a benchmark for evaluating both experimental and theoretical estimates of vertical ionization potentials for the 53 molecules studied. </div> </div> </div>

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Zero Point Energy

Van Nostrand's Scientific Encyclopedia ◽

10.1002/0471743984.vse7649 ◽

2005 ◽

Keyword(s):

Zero Point ◽

Zero Point Energy ◽

Point Energy

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Zero-point energy of linear triatomic molecules

Journal of the Chemical Society Faraday Transactions 2 Molecular and Chemical Physics ◽

10.1039/f29747000871 ◽

1974 ◽

Vol 70 ◽

pp. 871 ◽

Cited By ~ 2

Author(s):

Jan Bron

Keyword(s):

Zero Point ◽

Zero Point Energy ◽

Point Energy ◽

Triatomic Molecules

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An investigation into the existence of zero-point energy in the Rock-Salt Lattice by an X-Ray Diffraction Method

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1928.0055 ◽

1928 ◽

Vol 118 (779) ◽

pp. 334-350 ◽

Cited By ~ 41

Keyword(s):

Rock Salt ◽

Diffraction Method ◽

Zero Point ◽

Temperature Factor ◽

X Rays ◽

Zero Point Energy ◽

Chlorine Atoms ◽

Point Energy ◽

X Ray ◽

State Of Rest

In the present paper we shall attempt to collate the results of four separate lines of research which, taken together, appear to provide some interesting checks between theory and experiment. The investigations to be considered are (1) the discussion by Waller* and by Wentzel,† on the basis of the quantum (wave) mechanics, of the scattering of radiation by an atom ; (2) the calculation by Hartree of the Schrödinger distribution of charge in the atoms of chlorine and sodium ; (3) the measurements of James and Miss Firth‡ of the scattering power of the sodium and chlorine atoms in the rock-salt crystal for X-rays at a series of temperatures extending as low as the temperature of liquid air ; and (4) the theoretical discussion of the temperature factor of X-ray reflexion by Debye§ and by Waller.∥ Application of the laws of scattering to the distribution of charge calculated for the sodium and chlorine atoms, enables us to calculate the coherent atomic scattering for X-radiation, as a function of the angle of scattering and of the wave-length, for these atoms in a state of rest, assuming that the frequency of the X-radiation is higher than, and not too near the frequency of the K - absorption edge for the atom.¶ From the observed scattering power at the temperature of liquid air, and from the measured value of the temperature factor, we can, by applying the theory of the temperature effect, calculate the scattering power at the absolute zero, or rather for the atom reduced to a state of rest. The extrapolation to a state of rest will differ according to whether we assume the existence or absence of zero point energy in the crystal lattice. Hence we may hope, in the first place to test the agreement between the observed scattering power and that calculated from the atomic model, and in the second place to see whether the experimental results indicate the presence of zero-point energy or no.

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