Electric dipole rovibrational transitions in HD molecule

The rovibrational electric dipole transitions in the ground electronic state of the HD molecule are studied. A simple, yet rigorous formula is derived for the transition rates in terms of the electric dipole moment function $D(R)$, which is calculated in a wide range of $R$. Our numerical results for transition rates are in moderate agreement with experiments and previous calculations, but are at least an order of magnitude more accurate.Comment: 7 pages, 1 figur

ASSESSMENT OF GEOMETRIC ACCURACY OF VHR SATELLITE IMAGES

VHR images of earths ’ surface are more frequently used and taken advantage of in substitution to aerial photographs. Geometric dependences of creation orthophoto based on aerial photos are known and distinguished from images of VHR. Results of work led are presented in this article within the confines of an investigative project under the Committee of Scientific Research of Poland concerning the geometric mechanism of VHR images and corrections. Two test fields have been made up for this project (city, country and mountain terrain). For those test fields, images from IKONOS, QuickBird were ordered. In the conducted research the angle of the axes was take into consideration: 0 ° – 15 ° In each test field area, after the identification of control points on the VHR images, about 30 – 90 GCP have been measured with GPS in accuracy of 10 cm. For image geometric corrections in this project two types of available DTM models in Poland have been applied with varying accuracy. Geometric correction have been realized with the aid of generally available software as PCI Geomatica 9 with taking into consideration RPC method and camera ( rigorous) model. Throughout the work investigated, in each of the individual scenes of VHR various distribution and number of GCP was utilized for the process of orthorectification. Accuracy of orthorectification process received in result of led work, for VHR images at different configuration of geometry and methodology. Detailed results of experiments allow determining the optimal foundation for different methods of geometric corrections from IKONOS, QuickBird images and establishing effective process of dependence and defining geometric accuracy for different applications. 1

Double-well states of ungerade symmetry in H-2: First observation and comparison with ab initio calculations

A class of long-lived outer well states of ungerade symmetry lying above the ionization threshold in molecular hydrogen is investigated. A triple resonance scheme is used to study the rovibrational levels within a potential extended over internuclear separations. Good agreement with updated ab initio calculations is found. This demonstrates that for as long as the interaction with the Rydberg manifolds is shielded by a barrier, such calculations can be extended to an energetic range above the ionization

Low-energy Antiproton Interaction with Helium

An ab initio potential for the interaction of the neutral helium atom with antiprotons and protons is calculated using the Born-Oppenheimer approximation. Using this potential, the annihilation cross section for antiprotons in the energy range 0.01 microvolt to 1 eV is calculated.Comment: 13 pages, 7 figures, LaTe

Calculations of exchange interaction in impurity band of two-dimensional semiconductors with out of plane impurities

We calculate the singlet-triplet splitting for a couple of two-dimensional electrons in the potential of two positively charged impurities which are located out of plane. We consider different relations between vertical distances of impurities $h_1$ and $h_2$ and their lateral distance $R$. Such a system has never been studied in atomic physics but the methods, worked out for regular two-atomic molecules and helium atom, have been found to be useful. Analytical expressions for several different limiting configurations of impurities are obtained an interpolated formula for intermediate range of parameters is proposed. The $R$-dependence of the splitting is shown to become weaker with increasing $h_1,h_2$.Comment: 14 pages, RevTeX, 5 figures. Submitted to Phys Rev.

Centre-of-mass separation in quantum mechanics: Implications for the many-body treatment in quantum chemistry and solid state physics

We address the question to what extent the centre-of-mass (COM) separation can change our view of the many-body problem in quantum chemistry and solid state physics. It was shown that the many-body treatment based on the electron-vibrational Hamiltonian is fundamentally inconsistent with the Born-Handy ansatz so that such a treatment can never respect the COM problem. Born-Oppenheimer (B-O) approximation reveals some secret: it is a limit case where the degrees of freedom can be treated in a classical way. Beyond the B-O approximation they are inseparable in principle. The unique covariant description of all equations with respect to individual degrees of freedom leads to new types of interaction: besides the known vibronic (electron-phonon) one the rotonic (electron-roton) and translonic (electron-translon) interactions arise. We have proved that due to the COM problem only the hypervibrations (hyperphonons, i.e. phonons + rotons + translons) have true physical meaning in molecules and crystals; nevertheless, the use of pure vibrations (phonons) is justified only in the adiabatic systems. This fact calls for the total revision of our contemporary knowledge of all non-adiabatic effects, especially the Jahn-Teller effect and superconductivity. The vibronic coupling is responsible only for removing of electron (quasi)degeneracies but for the explanation of symmetry breaking and forming of structure the rotonic and translonic coupling is necessary.Comment: 39 pages, 11 sections, 3 appendice

Hydrogen molecule in a magnetic field: The lowest states of the Pi manifold and the global ground state of the parallel configuration

The electronic structure of the hydrogen molecule in a magnetic field is investigated for parallel internuclear and magnetic field axes. The lowest states of the $\Pi$ manifold are studied for spin singlet and triplet$(M_s = -1)$ as well as gerade and ungerade parity for a broad range of field strengths $0 \leq B \leq 100 a.u.$ For both states with gerade parity we observe a monotonous decrease in the dissociation energy with increasing field strength up to $B = 0.1 a.u.$ and metastable states with respect to the dissociation into two H atoms occur for a certain range of field strengths. For both states with ungerade parity we observe a strong increase in the dissociation energy with increasing field strength above some critical field strength $B_c$. As a major result we determine the transition field strengths for the crossings among the lowest $^1\Sigma_g$, $^3\Sigma_u$ and $^3\Pi_u$ states. The global ground state for $B \lesssim 0.18 a.u.$ is the strongly bound $^1\Sigma_g$ state. The crossings of the $^1\Sigma_g$ with the $^3\Sigma_u$ and $^3\Pi_u$ state occur at $B \approx 0.18$ and $B \approx0.39 a.u.$, respectively. The transition between the $^3\Sigma_u$ and $^3\Pi_u$ state occurs at $B \approx 12.3 a.u.$ Therefore, the global ground state of the hydrogen molecule for the parallel configuration is the unbound $^3\Sigma_u$ state for $0.18 \lesssim B \lesssim 12.3 a.u.$ The ground state for $B \gtrsim 12.3 a.u.$ is the strongly bound $^3\Pi_u$ state. This result is of great relevance to the chemistry in the atmospheres of magnetic white dwarfs and neutron stars.Comment: submitted to Physical Review

Two-Center Integrals for r_{ij}^{n} Polynomial Correlated Wave Functions

All integrals needed to evaluate the correlated wave functions with polynomial terms of inter-electronic distance are included. For this form of the wave function, the integrals needed can be expressed as a product of integrals involving at most four electrons

Correlated sampling in quantum Monte Carlo: a route to forces

In order to find the equilibrium geometries of molecules and solids and to perform ab initio molecular dynamics, it is necessary to calculate the forces on the nuclei. We present a correlated sampling method to efficiently calculate numerical forces and potential energy surfaces in diffusion Monte Carlo. It employs a novel coordinate transformation, earlier used in variational Monte Carlo, to greatly reduce the statistical error. Results are presented for first-row diatomic molecules.Comment: 5 pages, 2 postscript figure

A Search for Mid-Infrared Molecular Hydrogen Emission from Protoplanetary Disks

We observed the Herbig Ae/Be stars UX Ori, HD 34282, HD 100453, HD 101412, HD 104237 and HD 142666, and the T Tauri star HD 319139 and searched for H2 0-0 S(2) emission at 12.278 micron and H2 0-0 S(1) emission at 17.035 micron with VISIR, ESO-VLT's high-resolution MIR spectrograph. None of the sources present evidence for H2 emission. Stringent 3sigma upper limits to the integrated line fluxes and the mass of optically thin warm gas in the disks are derived. The disks contain less than a few tenths of Jupiter mass of optically thin H2 gas at 150 K at most, and less than a few Earth masses of optically thin H2 gas at 300 K and higher temperatures. We compare our results to a Chiang and Goldreich (1997, CG97) two-layer disk model. The upper limits to the disk's optically thin warm gas mass are smaller than the amount of warm gas in the interior layer of the disk, but they are much larger than the amount of molecular gas in the surface layer. We present a calculation of the expected thermal H2 emission from optically thick disks, assuming a CG97 disk structure, a gas-to-dust ratio of 100 and Tgas = Tdust. The expected H2 thermal emission fluxes from typical disks around Herbig Ae/Be stars (10^-16 to 10^-17 erg/s/cm2 at 140 pc) are much lower than the detection limits of our observations (5*10^-15 erg/s/cm2). H2 emission levels are very sensitive to departures from the thermal coupling between the molecular gas and dust. Additional sources of heating of gas in the disk's surface layer could have a major impact on the expected H2 disk emission. In the observed sources the molecular gas and dust in the surface layer have not significantly departed from thermal coupling (Tgas/Tdust< 2) and that the gas-to-dust ratio in the surface layer is very likely lower than 1000.Comment: 16 pages, 9 figures, accepted by A&A. v2: typo in footnote ** corrected, v3: corrections of the A&A language editor included, typo in title of Fig. 1. correcte