Calculation of the rotational energies of the H2O molecule from a force field

The rotational energy levels up to J,K?10 are calculated for the lowest vibrational state of the water molecule. A rapidly convergent model of the effective rotational Hamiltonian is used.     

Calculation of dispersion energies

We summarize the theory of van der Waals (dispersion) forces, with emphasis on recent microscopic approaches that permit the prediction of forces between solids and nanostructures right down to intimate contact and binding. Some connections are pointed out between microscopic theory and macroscopic Lifshitz theory.     

Stability of nuclear rotational states

The stability of rotational states described by using a procedure of the Hartree-Fock-Bogoliubov method is discussed. The stability condition is obtained in a general form and some of its properties are examined with the aid of simplifying approximations. It is pointed out in conclusion that the Coriolis force might lead to the instability of rotational states for sufficiently large angular momenta. The instability of rotational states is caused by the instability of the pairing density, and also by that of the nuclear density distribution. In the former case it is shown that below the critical angular momentum, a first-order phase transition takes place and in some cases the rotational band breaks off. In the latter case, it might be considered that the assumption of an axially symmetric deformation is broken or large change of the equilibrium deformation is brought suddenly. Then discontinuous change of the rotational level might be seen at the unstable point.     

ZnO薄膜的激子能量和束缚能的计算

采用有效质量近似，将耦合在一起的6×6价带本征方程分开来考虑, 取激子试探波函数为z方向和x-y平面分离的形式，用变分法计算了ZnO薄膜重空穴带激子基态能、第一激发态能、束缚能和激子的半径随薄膜厚度的变化关系，并讨论了电子波函数的量子隧穿效应对厚度d<2.0 nm薄膜的能量修正. 关键词： 激子 ZnO薄膜 纤锌矿     

Nonadiabatic corrections to the rotational energies of the hydrogen molecule

Nonadiabatic corrections to the rotational energies and rotational constants B_ν have been computed by a variational perturbation method for several vibrational levels of the H₂, HD, and D₂ molecules. It is believed that the convergence error in the computed corrections to the energy is less than 10^?3 cm^?1. The corrections improve the agreement of theoretical and experimental rotational quanta, but there are still discrepancies that amount in some cases to a few hundredths of a cm^?1. These discrepancies are irregular and it is argued that they are at least partly due to experimental inaccuracies.     

Asymptotic behavior of rotational energies of rigid X2Y-type molecules

In this study the asymptotic behavior of rotational energies of simple rigid molecules of X₂Y-type is considered. This behavior is obtained using various forms of an effective rotational Hamiltonian. The results of calculations for highly excited rotational energies of the molecules H₂O and CH₂ are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 9–12, January, 1990.     

Complex shape effects in nuclear rotational spectra

We study the evolution of collectivity in the structure of nuclear rotational bands based on complex quadrupole-octupole shapes. We apply an extended version of a quadrupole-octupole rotation model capable of reproducing both the low-lying states of alternating parity bands interpreted on the basis of octupole vibrations and the higher spin states considered as members of a single octupole rotational band. In such a way, the complicated odd-even staggering effects observed in light actinide nuclei are described successfully. The implemented model analysis suggests a unified mechanism in which the octupole band structure is formed as the result of the transition from an octupole vibration (soft) mode to a rotation of a shape with a stable quadrupole-octupole deformation.     

Coulomb contributions to nuclear radii and energies

The effect of including the isospin non-scalar Coulomb interaction (also taking into account the finite proton size) in binding energy and rms radius calculations for the closed shell nuclei ⁴He, ¹⁶O and ⁴⁰Ca is discussed in detail. Using the saturating Sussex matrix elements and including 0 + 2?ω excitations it is found that the major Coulomb contribution is in the first order, and that the pure second-order Coulomb contribution to the energy, near the saturation value of the size parameter for each nucleus, is more important than the mixed second-order contribution. Finally, for third order and above one can safely neglect the pure Coulomb contributions compared to the mixed ones which are in turn small compared to the pure nuclear contribution, in that order.     

Ideal nuclear fluid dynamics at ultra-relativistic energies

We investigate the reaction O+Au at 200 AGeV in an ideal relativistic (3+1)-dimensional one-fluid hydrodynamical model. We correct former calculations which contained acausal matter transport, leading to contradictions with experimental data for the baryonic rapidity distribution. We find that the corrected results are in good agreement with data, casting new light on the question of the applicability of ideal one-fluid hydrodynamics to heavy-ion collisions.     

Correlated variations of nuclear radii and binding energies

In the present work we establish a correlation between variations of nuclear radii and binding energies as functions of particle numbers. Limitations and connections with other models are also discussed.     

Coulomb energies and charge asymmetry of nuclear forces

Charge-symmetry-breaking potentials suggested in the literature to resolve the discrepancy between calculated Coulomb energy differences of analog states and the experimental values, are considered in detail. We calculate the contributions of these potentials to the ground state energy differences of the mirror nuclei ³He³H, ¹⁵O¹⁵N, ¹⁷F¹⁷O, ³⁹Ca³⁹K and ⁴¹Sc⁴¹Ca. It turns out, due to the short range character of these symmetry-breaking potentials, that their inclusion may resolve the ³He³H difficulty but not the ⁴¹Sc⁴¹Ca discrepancy.     

Calculation of elastic electron-helium scattering at intermediate energies

The two-potential eikonal approximation is applied to the calculation of the differential cross section for elastic scattering of electrons by ground state helium atoms at energies 50 and 100 rV. The results agree very well with experiments.     

Direct photons in nuclear collisions at fair energies

Using the extrapolation of existing data, estimations of prompt-photon production at FAIR energies have been made. At y = y _c.m. the rapidity density of prompt photons with p _t > 1.5 GeV/c per central Au + Au event at 25 A GeV is estimated as ∼10⁻⁴. With the planned beam intensity 10⁹ per second and 1% interaction probability, for 10% of most central events one can expect the prompt-photon rate ∼10² photons per second. Direct photons from the hadron scenario of ion collisions generated by the Hadron-String-Dynamics (HSD) transport approach with implemented meson scatterings πρ → πγ, ππ → ργ have been analyzed. Photons from short-living resonances (e.g., ω → π ⁰ γ) decaying during the dense phase of the collision should be considered as direct photons. They contribute significantly in the directphoton spectrum at p _t = 0.5–1 GeV/c. At the FAIR energy 25 A GeV in Au + Au central collisions the HSD generator predicts, as a lower estimate, γ _direct/ ≃ 0.5% in the region p _t = 0.5–1 GeV/c. At p _t = 1.5–2 GeV/c γ _prompt/ ≃ 2%. Thermal direct photons have been evaluated with the Bjorken Hydro-Dynamics (BHD) model. The BHD spectra differ strongly from the HSD predictions. The direct-photon spectrumis very sensitive to the initial temperature parameter T ₀ of the model. The 10-MeV increase in the T ₀ value leads to ∼2 times higher photon yield. The text was submitted by the authors in English.     

Wave-spreading effects in nuclear scattering at intermediate energies

Based on the Fresnel approach discussed in a previous article the S-matrix for nuclear elastic scattering is factorized into an infinite product, the n-th term of which is essentially given by (n ? 1)-fold commutators of the interaction potential at n different z-coordinate positions. A subsequent cumulant expansion expresses the Fresnel phase shift as an infinite sum of many-body clusters. In constrast to eikonal-type expansions each term of this sum contains contributions of all orders in the inverse wave number. Because of this feature the present expansion is useful for scattering from light nuclei over a wide range of energies and scattering angles.     

Calculation of the energies of torsional states for dihydroxybenzenes

We present theoretical models and results of calculations of the energies of torsional states of dihydroxybenzenes: flexible molecules with two non-coaxial internal tops of low symmetry. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 178–183, March–April, 2007.