Search results for "Wave function"
showing 10 items of 395 documents
Relativistic corrections to the vector meson light front wave function
2020
We compute a light front wave function for heavy vector mesons based on long distance matrix elements constrained by decay width analyses in the Non Relativistic QCD framework. Our approach provides a systematic expansion of the wave function in quark velocity. The first relativistic correction included in our calculation is found to be significant, and crucial for a good description of the HERA exclusive $\mathrm{J}/\psi$ production data. When looking at cross section ratios between nuclear and proton targets, the wave function dependence does not cancel out exactly. In particular the fully non-relativistic limit is found not to be a reliable approximation even in this ratio. The important…
QRPA estimate for the Δ (1232) contribution to the Gamow-Teller decay of heavy nuclei
1991
Abstract The contribution of the Δ (1232) isobars to the nuclear beta decay strength function is estimated in the framework of the charge-changing form of the QRPA. This procedure is applied to neutron-deficient tin isotopes. The results imply that the quenching of the low-energy Gamow-Teller decay strength cannot attributed to the presence of delta admixtures in the nuclear wave function.
Intermolecular potential and rovibrational states of the H2O–D2 complex
2012
International audience; A five-dimensional intermolecular potential for H2O-D-2 was obtained from the full nine-dimensional ab initio potential surface of Valiron et al. [P. Valiron, M. Wernli, A. Faure, L. Wiesenfeld, C. Rist, S. Kedzuch, J. Noga, J. Chem. Phys. 129 (2008) 134306] by averaging over the ground state vibrational wave functions of H2O and D-2. On this five-dimensional potential with a well depth D-e of 232.12 cm (1) we calculated the bound rovibrational levels of H2O-D-2 for total angular momentum J = 0-3. The method used to compute the rovibrational levels is similar to a scattering approach-it involves a basis of coupled free rotor wave functions for the hindered internal r…
Reducing CAS-SDCI space. Using selected spaces in configuration interaction calculations in an efficient way
2002
A new method is presented, which allows an important reduction of the size of some Configuration Interaction (CI) matrices. Starting from a Complete Active Space (CAS), the numerous configurations that have a small weight in the CAS wave function are eliminated. When excited configurations (e.g., singly and doubly excited) are added to the reference space, the resulting MR-SDCI space is reduced in the same proportion as compared with the full CAS–SDCI. A set of active orbitals is chosen, but some selection of the most relevant excitations is performed because not all the possible excitations act as SDCI generators. Thanks to a new addressing technique, the computational time is drastically …
Energy-weighted M1 sum rule with explicit δ degrees of freedom
1985
Abstract The influence of Δ degrees of freedom on the energy-weighted M1 sum rule is investigated and applied to 2 H and 4 He. Using π- and ρ-exchange potentials a reduction of the potential contribution of the order of 50% is obtained. The absolute value of the sum rule is strongly dependent on the short-range behaviour of the nuclear wave function. Furthermore, the contribution of c.m. effects is evaluated and found to be of the order of 5–10%.
Nonlocal chiral quark models with wavefunction renormalization: Sigma properties andπ−πscattering parameters
2008
We analyze the sigma meson mass and width together with the pion-pion scattering parameters in the context of nonlocal chiral quark models with wave function renormalization (WFR). We consider both nonlocal interactions based on the frequently used exponential form factor, and on fits to the quark mass and renormalization functions obtained in lattice calculations. In the case of the sigma properties, we obtain results which are less dependent on the parametrization than in the standard local Nambu-Jona-Lasinio model, and which are in reasonable agreement with the recently reported empirical values. We also show that the inclusion of the WFR tend to improve the description of the $\ensurema…
Scattering amplitudes and integral equations for the collision of two charged composite particles
1980
Transition operators for the collision of two clusters composed of an arbitrary number of charged and neutral particles are represented as a sum of pure Coulomb and Coulomb-modified short-range operators. Sandwiching this relation between the corresponding channel states, correct two-fragment scattering amplitudes are obtained by adapting the conventional two-body screening and renormalization procedure. Furthermore, integral equations are derived for off-shell extensions of the full screened amplitudes and of the unscreened Coulomb-modified short-range amplitudes. For three particles, the final results coincide with those derived previously in a different approach. The proposed theory is v…
Computational determination of the dominant triplet population mechanism in photoexcited benzophenone
2014
In benzophenone, intersystem crossing occurs efficiently between the S-1(n pi(star)) state and the T-1 state of dominant n pi(star) character, leading to excited triplet states after photoexcitation. The transition mechanism between S-1(n pi(star)) and T-1 is still a matter of debate, despite several experimental studies. Quantum mechanical calculations have been performed in order to assess the relative efficiencies of previously proposed mechanisms, in particular, the direct S-1 -> T-1 and indirect S-1 -> T-2(pi pi(star)) -> T-1 ones. Multiconfigurational wave function based methods are used to discuss the nature of the relevant states and also to determine minimum energy paths a…
Pion-induced η production on nuclei
1990
Abstract Low-energy η production on nuclei is investigated in a DWIA framework, using a Green function method. The η potential is constructed by folding medium-modified η N → S 11 → η N scattering amplitudes with nuclear wave functions. A phenomenological spreading potential is introduced for the intermediate S 11 resonance. Calculated ( π + , p ) η cross sections on 12 C and 16 O with the spreading potential having an imaginary part of the order of −50 ∼ −100 MeV compare favorably with recent experimental data. It is also shown that the energy dependence of the ( π + , η ) inclusive spectra is nicely reproduced, though the magnitude is somewhat underestimated.
Theoretical investigations of the IR spectroscopy of Ni(C(2)S(2)H(2))(2). A case study of the P_VMWCI(2) algorithm including anharmonic effects.
2010
The near infrared (NIR) spectra of bis(ethylene-1,2-dithiolato)nickel, Ni(C(2)S(2)H(2))(2) are fully interpreted here by applying a method developed for efficient automatic computation of both the infrared wave numbers and the intensities. The employed procedure uses parallel variational multiple window configuration interaction wave functions, the so-named P_VMWCI(2) algorithm, which incorporates both the mechanical and the electric anharmonic effects. It is shown that inclusion of anharmonicities is crucial for correctly assigning the fundamental, combination, and overtone vibrational frequencies in the infrared spectrum of the target system, for which conflicting assignments are found in…