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From a comparison of the spectra of CH and other molecules toward the continuum source Cas A and four dark clouds, the ground state transition frequencies of CH have been determined and are reported. The relative errors in these frequencies are about twice as small as those obtained earlier by radio astronomical methods for the two main lines of ground state OH.
Different-orbitals-for-different-spins wave function for singlet S ground state of He expressed in Shull and Loewdin basis orbitals
Rayleigh-Schroedinger perturbation calculations for ground state of one-electron helium-hydrogen molecular ion
Spectroscopic reassignment and ground state dissociation energy of molecular iodine
Spectroscopic reassignment and ground state dissociation energy of molecular iodine
Population inversion in Cs133 ground state hyperfine levels, using CW GaAs laser at 77 K for optical pumping
The present work investigates analytically the effect of an intermediate or intense magnetic field, such as probably exist in white dwarfs and near pulsars, on the binding energy of the hydrogen ground state. A wave-function 'prescription' is given for an analytic variational calculation of the binding energy. The calculation still gives a smooth transition between intermediate and intense fields. An explicit calculation of the ground-state binding energy as B goes to infinity is provided for the Yafet et al. (1956) trial function.
Perturbation expansions for ground state function of helium atom, using Hartree or Hartree-Fock model Hamiltonian, based on Weiss-Martin variation-perturbation calculation
The accurate first-principles description of strongly-correlated materials is an important and challenging problem in condensed matter physics. Ab initio downfolding has emerged as a way of deriving accurate many-body Hamiltonians including strong correlations, representing a subspace of interest of a material, using density functional theory calculations as a starting point. However, the solution of these material-specific models can scale exponentially on classical computers, constituting a challenge. Here we propose that utilizing quantum computers for obtaining the properties of downfolded Hamiltonians yields an accurate description of the ground state properties of strongly-correlated systems, while circumventing the exponential scaling problem. We benchmark the solution of Hubbard-like models obtained through downfolding by utilizing a classical tensor network implementation of variational quantum eigensolvers (VQE), and we reveal a strategy for driving the optimization through a hybrid minimization of the energy and maximization of the overlap with an approximate solution obtained through low-cost computational methods. This results in a reduction of the energy error by orders of magnitude compared to conventional VQE approaches, and allows us to reproduce long-range correlations for the first time. We demonstrate our first-principles approach for diverse strongly-correlated materials, correctly predicting the antiferromagnetic state of one-dimensional cuprate Ca 2 CuO 3 , the excitonic ground state of monolayer WTe2, and the charge-ordered state of correlated metal SrVO 3 . Our efficient computational implementation allows us to simulate large systems with up to 54 qubits and encompassing up to four correlated bands, which is indicative of the complexity that our framework can address.
Re2(CO)6(dmpm)2 shows photophysical behavior in a rigid medium that differs dramatically from that observed in fluid solution. In a hydrocarbon glass at 77 K, metal-metal bond homolysis is suppressed and an intense phosphorescence is observed. The transient absorption spectrum, which shows only weak transitions to the red of the ground state 1(sigma-sigma asterisk) transition, permits assignment of the emitting state to a 3(sigma-sigma asterisk) transition. The crystal structure of Re2(CO)6(dmpm)2 is also reported. The ground-state electronic structure is discussed relative to the structural data.
The NH3 far infrared spectrum is particularly useful for the study of planetary composition and atmospheric dynamics. Studies of this spectrum were conducted by Dowling (1969), Helminger et al. (1971), and Urban et al. (1981). Sattler et al. (1981) have reported measurements of a few nu2 lines with tunable diode lasers. By using simple sum rules, these lines and accurate ground state inversion lines considered by Poynter and Kakar (1975) have been employed in the present investigation to deduce a few of the far infrared ground state transitions. An extensive set of high signal/noise, high resolution (0.0048 per cm) scans of the nu2 bands of NH3 from about 600 per cm through about 1300 per cm ait a series of low pressures have been made in order to accurately determine both the line positions and strengths. The obtained data provide line positions with an absolute accuracy of about 0.0001 per cm in the more favorable cases.
Paramagnetic energy levels of ground state of chromium 3 and aluminum oxides
Oscillator strength of resonance transitions of ground state nitrogen and oxygen
Potential energy curves for O - O interactions corresponding to the X (sup 3) Sigma - g, 1 delta g, 1 Sigma plus g, 3 delta u, A3 Sigma plus u, 1 Sigma - u, and B3 Sigma states of O (sub 2) have been calculated from spectroscopic data by the Rydberg‐Klein‐Rees method. Curves for the remaining twelve states of O (sub 2) dissociating to ground state atoms have been obtained from relations derived from approximate quantum‐mechanical calculations, and checked against the meager experimental information available. Two semi‐independent calculations have been made, and are in good agreement with each other. The quantum‐mechanical relations also lead to an approximate O (sub 2) - O (sub 2) interaction, which is consistent with interactions derived from vibrational relaxation times and from high‐temperature gas viscosity data.
Ground state energy of Anderson Hamiltonian calculated by cluster variation for cases of infinite d-d correlation energy
Vibrational energies, rotational constants and internuclear potential of ground state molecular iodine, using reanalyzed spectroscopic data
Evidence is presented that some previous studies of reactions of O(2+) ions with various atoms and molecules referred to ion samples composed in part of ions in metastable (1D and/or 1S) states. This finding resolves the 3 orders of magnitude discrepancy between previous experimental and calculated rate coefficients for the O(2+)(3P) + He charge transfer process. Using a drift tube to distinguish, via arrival time differences, groundstate O(+)(3P) and metastable ions, a rate coefficient of (3.5 plus or minus 1.5) x 10 to the -11th cu cm/sec is obtained for the reaction, in good agreement with that obtained from ab initio theoretical calculations. Previous conclusions concerning reactions of O(2+) with O2 and N2, however, remain valid since the difference in reactivity of ground-state and metastable O(2+) ions appears to be negligible in this case. The rate coefficient for the reaction O(2+) + CO2 has been determined to be (2 plus or minus 0.5) x 10 to the -9th cu cm/sec for ions either in the ground-state or in metastable states.
Most of the important chemical reactions which occur in the very high temperature air produced around space vehicles as they enter the atmosphere were investigated both experimentally and theoretically, to some extent at least. One remaining reaction about which little is known, and which could be quite important at the extremely high temperatures that will be produced by the class of space vehicles now contemplated - such as the AOTV - is the excitation of bound electron states due to collisions between heavy gas particles. Rates of electronic excitation due to free electron collisions are known to be very rapid, but because these collisions quickly equilibrate the free and bound electron energy, the approach to full equilibrium with the heavy particle kinetic energy will depend primarily on the much slower process of bound electron excitation in heavy particle collisions and the subsequent rapid transfer to free electron energy. This may be the dominant mechanism leading to full equilibrium in the gas once the dissociation process has depleted the molecular states so the transfer between molecular vibrational energy and free electron energy is no longer available as a channel for equilibration of free electron and heavy particle kinetic energies. Two mechanisms seem probable in electronic excitation by heavy particle impact. One of these is the collision excitation and deexcitation of higher electronic states which are Rydberg like. A report, entitled 'Semi-Classical Theory of Electronic Excitation Rates', was submitted previously. This presented analytic expressions for the transition probabilities, assuming that the interaction potential is an exponential repulsion with a perturbation ripple due to the dipole-induced dipole effect in the case of neutral-neutral collisions, and to the ion-dipole interaction in the case of ion-neutral collisions. However the above may be, there is little doubt that excitation of ground state species by collision occurs at the point where the initial and final potentials cross, or at least come very close. Therefore, this mechanism would be applicable to the case where a gas is initially at very low temperature suddenly subjected to high energy heavy particle bombardment. This situation would model the measurement of excitation cross section by molecular beam techniques, for example. The purpose is to report values of cross sections and rate coefficients for collision excitation of ground state atoms estimated with the Landau-Zener transition theory and to compare results with measurement of excitation cross sections for a beam of Hydrogen atoms impacting Argon atom targets. Some very dubious approximations are used, and the comparison with measurement is found less than ideal, but results are at least consistent within order of magnitude. The same model is then applied to the case of N-N atom collisions, even though the approximations then become even more doubtful. Still the rate coefficients obtained are at least plausible in both magnitude and functional form, and as far as I am aware these are the only estimates available for such rate coefficients.