Polarization propagator calculations with an AGP reference state

1984 ◽  
Vol 80 (5) ◽  
pp. 2009-2021 ◽  
Author(s):  
B. Weiner ◽  
Hans‐Jo/rgen Aa. Jensen ◽  
Y. Öhrn
Keyword(s):  
Reference State ◽  
Polarization Propagator

scholarly journals Erratum: Polarization propagator calculations with AGP reference state [J. Chem. Phys. 80, 2009 (1984)]

1984 ◽  
Vol 81 (1) ◽  
pp. 587-587 ◽  
Author(s):  
B. Weiner ◽  
H. J. A. Jensen ◽  
Y. Öhrn
Keyword(s):  
Chem Phys ◽  
Reference State ◽  
Polarization Propagator

scholarly journals Electronic circular dichroism spectra using the algebraic diagrammatic construction schemes of the polarization propagator up to third order

2021 ◽  
Vol 154 (6) ◽  
pp. 064107
Author(s):  
Mikael Scott ◽  
Dirk R. Rehn ◽  
Sonia Coriani ◽  
Patrick Norman ◽  
Andreas Dreuw
Keyword(s):  
Circular Dichroism ◽  
Circular Dichroism Spectra ◽  
Third Order ◽  
Electronic Circular Dichroism ◽  
Polarization Propagator ◽  
Circular Dichroïsm

Through-Space Transmission of 19F-13C Coupling Via an Intermediate Bond. An Experimental and Theoretical Study

1987 ◽  
Vol 40 (12) ◽  
pp. 1923 ◽  
Author(s):  
ID Rae ◽  
ID Rae ◽  
A Staffa ◽  
A Staffa ◽  
AC Diz ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Lone Pair ◽  
Electron Excitation ◽  
Carbonyl Groups ◽  
Polarization Propagator ◽  
Close Proximity ◽  
Fermi Contact ◽  
Intramolecular Hydrogen ◽  
Intermediate Bond ◽  
Insight Into

In order to obtain a deeper insight into the title effect, several compounds with an F atom very close to a C-H of a nearby functional group were synthesized and the relevant couplings measured. The most conspicuous case was that of 8-fluoro-2-hydroxynaphthalene-1-carbaldehyde where a close proximity between the F and H atoms is the result of fluorine-oxygen repulsion and the formation of an intramolecular hydrogen bond between the hydroxyl and carbonyl groups. The experimental four-bond J(F,CHO) coupling is 26.2 Hz. A compound very similar to this one, but without the OH group, was chosen on which to perform a polarization propagator analysis of the through-space (TS) coupling pathways, at the RPA-INDO level. The expression for the TS coupling in terms of the projected polarization propagator and perturbators was numerically analysed. It is found that this coupling is completely dominated by a TS component of the Fermi contact (FC) term, the main features of which are: ( i ) It decays exponentially with the F-H distance; (ii) Its main contribution comes from an electron excitation involving the F lone-pair, the C-H bond of the CHO moiety and its corresponding antibonding orbital;(iii) The π-type lone-pair does not contribute to the TS coupling pathway of the FC term.

scholarly journals Estimates of direct radiative forcing due to aerosols from the MERRA-2 reanalysis over the Amazon region

2018 ◽  
Author(s):  
Brunna Penna ◽  
Dirceu Herdies ◽  
Simone Costa
Keyword(s):  
Radiative Forcing ◽  
Reanalysis Data ◽  
Amazon Region ◽  
Reference State ◽  
Aerosol Radiative Forcing ◽  
Aerosol Loading ◽  
Direct Radiative Forcing ◽  
Direct Forcing ◽  
The Difference ◽  
Natural Aerosols

Abstract. Sixteen years of analysis of clear-sky direct aerosol radiative forcing is presented for the Amazon region, with calculations of AERONET network, MODIS sensor and MERRA-2 reanalysis data. The results showed that MERRA-2 reanalysis is an excellent tool for calculating and providing the spatial distribution of aerosol direct radiative forcing. In addition, the difference between considering the reference state of the atmosphere without aerosol loading and with natural aerosol to obtain the aerosol direct radiative forcing is discussed. During the dry season, the monthly average direct forcing at the top of atmosphere varied from −9.60 to −4.20 Wm−2, and at the surface, it varied from −29.81 to −9.24 Wm−2, according to MERRA-2 reanalysis data and the reference state of atmosphere without aerosol loading. Already with the state of reference being the natural aerosols, the average direct forcing at the top of atmosphere varied from −5.15 to −1.18 Wm−2, and at the surface, it varied from −21.28 to −5.25 Wm−2; this difference was associated with the absorption of aerosols.

scholarly journals First Principles Calculations of Defects in Unstable Crystals: Austenitic Iron

2011 ◽  
Vol 1363 ◽  
Author(s):  
G.J. Ackland ◽  
T.P.C. Klaver ◽  
D.J. Hepburn
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Defect Formation ◽  
Single Layer ◽  
Temperature Limit ◽  
Reference State ◽  
First Principles Calculations ◽  
General Picture ◽  
Bcc Iron ◽  
Defect Energies

ABSTRACTFirst principles calculations have given a new insight into the energies of point defects in many different materials, information which cannot be readily obtained from experiment. Most such calculations are done at zero Kelvin, with the assumption that finite temperature effects on defect energies and barriers are small. In some materials, however, the stable crystal structure of interest is mechanically unstable at 0K. In such cases, alternate approaches are needed. Here we present results of first principles calculations of austenitic iron using the VASP code. We determine an appropriate reference state for collinear magnetism to be the antiferromagnetic (001) double-layer (AFM-d) which is both stable and lower in energy than other possible models for the low temperature limit of paramagnetic fcc iron. Another plausible reference state is the antiferromagnetic (001) single layer (AFM-1). We then consider the energetics of dissolving typical alloying impurities (Ni, Cr) in the materials, and their interaction with point defects typical of the irradiated environment. We show that the calculated defect formation energies have fairly high dependence on the reference state chosen: in some cases this is due to instability of the reference state, a problem which does not seem to apply to AFM-d and AFM-1. Furthermore, there is a correlation between local free volume magnetism and energetics. Despite this, a general picture emerge that point defects in austenitic iron have geometries similar to those in simpler, non-magnetic, thermodynamically stable FCC metals. The defect energies are similar to those in BCC iron. The effect of substitutional Ni and Cr on defect properties is weak, rarely more than tenths of eV, so it is unlikely that small amounts of Ni and Cr will have a significant effect on the radiation damage in austenitic iron at high temperatures.

scholarly journals Coupled cluster analysis of the U(1) lattice gauge model using a correlated "mean-field" reference state

1996 ◽  
Vol 53 (5) ◽  
pp. 2610-2618 ◽  
Author(s):  
S. J. Baker ◽  
R. F. Bishop ◽  
N. J. Davidson
Keyword(s):  
Cluster Analysis ◽  
Mean Field ◽  
Reference State ◽  
Coupled Cluster ◽  
Gauge Model ◽  
Lattice Gauge
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