When using quantum chemistry techniques to calculate the energetics of bulk crystals, there is a need to calculate the Hartree-Fock (HF) energy of the crystal at the basis-set limit. We describe a strategy for achieving this, which exploits the fact that the HF energy of crystals can now be calculated using pseudopotentials and plane-wave basis sets, an approach that permits basis-set convergen...

[1] In recent years, large electron temperature increases of 300% (3000 K above background) caused by powerful HF-radio wave injection have been observed during nighttime using the EISCAT incoherent scatter radar near Tromsø in northern Norway. In a case study we examine the spatial structure of the modified region. The electron heating is accompanied by ion heating of about 100 degrees and mag...

The fact is noted that sufficiently high power density HF radio waves incident on the bottom side ionosphere will produce optical emissions. It was previously suggested that the mechanism for such excitation will switch from thermal electron collision excitation to supra-thermal electron collision excitation, as the ionospheric plasma density at the reflection height switches from much below 5 ...

In this paper,the molecular geometry for three tautomers of uracil and four tautomers of cytosine has been analyzed. vibrational IR spectra of the tautomers were   investigated at HF and B3LYP level using the AB initio 6-31G* and LANL2DZ basis sets from the program package Gaussian 98 (A.7 Public Domain version). The physico-chemical and biochemical properties of uracil and cytosine are one of...

The monitoring and regulation of one's own physiological reactions and cardioregulatory abnormalities are central to the aetiology and maintenance of social anxiety disorder (SAD). We therefore explored the neural correspondences of these heart rate alterations. 21 patients with SAD and 21 matched healthy controls (HCs) underwent 3T-fMRI scanning. Simultaneously, high-frequency heart rate varia...

High-frequency (HF) radars have been used since 20 years for remotely sensing ocean surface currents and ocean waves. Backscattered Doppler spectra contain two discrete lines, the frequencies of which (Bragg frequency) determine the current speed, and four continuous side bands, which allow to apply inversion techniques for retrieving ocean wave spectra. Recently, a new HF radar has been develo...

HF radar in ocean remote sensing makes use of electromagnetic waves of 10m to 100 m wavelength from the rough sea surface to measure surface current and ocean wave parameter. Recently, a new time division multiple frequency HF radar system called OSMAR2009 has been developed by the Wuhan University. One main advantage of the system is that it is of great help in extracting current parameters an...

Kohn–Sham (KS) and Hartree–Fock (HF) determinants were used as the true many-body wave functions for calculations of molecular energies, vibrational frequencies, and excited electronic states. The results justified common practice, encountered in the sum over states theories, in which these two determinants are used as the first-order approximation of the wave function. However, a distinct beha...

Observations of HF radar backscatter from artificial field-aligned irregularities in an ionosphere perturbed by travelling disturbances due to atmospheric gravity waves are presented. Some features of the spatio-temporal structure of the artificial radar backscatter can be explained in terms of the distortion of the ionosphere resulting from the travelling disturbances. The distorted ionosphere...

In this article we describe the unique insights into the electronic structure of molecules provided by generalized valence bond (GVB) theory. We consider selected prototypical hydrocarbons as well as a number of hypervalent molecules and a set of first- and second-row valence isoelectronic species. The GVB wave function is obtained by variationally optimizing the orbitals and spin coupling in t...