Zhang Qi-Ren

The Photoionization of Atomic Hydrogen in an Intense Circularly Polarized Laser Field

We calculate nonperturbatively the irfluence of a strong circularly polarized laser beam on the hydrogen atom energy levels by making use of the time-independent formalism proposed by one of us. The photoionization cross section of the hydrogen atom irradiated by this laser beam and the angular distribution of photoelectrons are also calculated. From the numerical results we clearly see the intensity dependence of the whole photoionization process,including the intensity dependence of the photoelectron energies.

Average Nuclear Binding Energies in a Lee–Wick Type Model

We find: (i) The Lee–Wick type relativistic mean-field theory with finite nucleon size effect can reproduce the binding energies for all nuclei over the nuclide table quite well. For 1654 nuclei, whose mass numbers range from 16 to 263 and charge numbers range from 8 to 106, the calculated binding energies are near to the corresponding experimental values with a systematical deviation of about 5.74%. (ii) The lowering of the calculated nuclear masses, by including Coulomb energy into the variational calculations, is very small.

Non-integer Quantum Transition, a True Non-perturbation Effect in Laser-Atom Interaction

Abstract We show that in the quantum transition of an atom interacting with an intense laser of circular frequencyω, the energy difference between the initial and the final states of the atom is not necessarily an integer multiple of thequantum energy ¯hω . This kind of non-integer transition is a true non-perturbation effect in laser-atom interaction.PACS numbers: 03.65.-w, 32.80.Fb, 32.90.+a, 33.60.-qKey words: transitions induced by intense lasers, non-perturbation effect, violation of Bohr condition 1 Introduction It is widely accepted that the Bohr conditionE 2 −E 1 = ±¯hω (1)expresses the energy conservation in the quantum transi-tion from the state with energy E 1 to the state with energyE 2 of the atom, interacting with the electromagnetic fieldof circular frequency ω. It may be generalized toE 2 −E 1 = N¯hω (2)with an integer N, when the atom is interacting with alaser. This generalized Bohr condition is still thought tobe an expression of the energy conservation in the tran-sition, with the number of absorbed or emitted photonsbeing larger than 1. The transitions satisfying Eq. (2)with N>1 have been observed experimentally in formsof the multi-photon ionization (MPI)

Potential Energy Surface of Cytosine and Tunneling Between Its Normal and Trans-imino Tautomer

The potential energy surface of H(13) proton in base cytosine of the DNA molecules is calculated at the Gaussian 98 MP2/6-311G(d,p) level. Two potential wells are found. One corresponds to the normal cytosine, while the other corresponds to its trans-imino tautomer. The estimated tunneling probability of the H(13) proton from one well to another well shows that the life time of the proton staying in one of these wells is about 600 yrs. It is too long to let tautomers of cytosine be in thermodynamical equilibrium in a room temperature gas phase experiment.

A Dynamical Description on Kapitza-Dirac Effect*

The Kapitza–Dirac effect is investigated in a formalism developed from the formal quantum theory. Numerical calculations yield good agreement with the experimental results.

Photo-Ionization of Hydrogen Atom in a Circularly Polarized Standing Electromagnetic Wave*

Applying time-independent non-perturbative formalism to the photo-ionization of hydrogen atom immersed in a strong circularly polarized standing electromagnetic wave, we calculate the shift of energy levels and the distortion of wave functions for the hydrogen atom, the ionization cross section induced by the standing wave, and the angular distribution of photoelectrons and obtain some interesting results.

Ionization of Atoms and the Thomas–Fermi Model for the Electric Field in Crystal Planar Channels*

The electric field in the crystal planar channels is studied by the Thomas–Fermi method. The Thomas–Fermi equation and the corresponding boundary conditions are derived for the crystal planar channels. The numerical solution for the electric field in the channels between (110) planes of the single crystal silicon and the critical angles of channelling protons in them are shown. Reasonable agreements with the experimental data are obtained. The results show that the Thomas–Fermi method for the crystal works well in this study, and a microscopic research of the channel electric field with the contribution of all atoms and the atomic ionization being taken into account is practical.

Quantum Corrections on Relativistic Mean Field Theory for Nuclear Matter

We propose a quantization procedure for the nucleon-scalar meson system, in which an arbitrary mean scalar meson field φ is introduced. The equivalence of this procedure with the usual ones is proven for any given value of φ. By use of this procedure, the scalar meson field in the Walecka’s RMFT and in Chin’s RHA are quantized around the mean field. Its corrections on these theories are considered by perturbation up to the second order. The arbitrariness of φ makes us free to fix it at any stage in the calculation. When we fix it in the way of Walecka’s RMFT, the quantum corrections are big, and the result does not converge. When we fix it in the way of Chin’s RHA, the quantum correction is negligibly small, and the convergence is excellent. It shows that RHA covers the leading part of quantum field theory for nuclear systems and is an excellent zeroth order approximation for further quantum corrections, while the Walecka’s RMFT does not. We suggest to fix the parameter φ at the end of the whole calculation by minimizing the total energy per-nucleon for the nuclear matter or the total energy for the finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a variational method.We propose a quantization procedure for the nucleon-scalar meson system, in which an arbitrary mean scalar meson field is introduced. The equivalence of this procedure with the usual one is proven for any given value of . By use of this procedure, the scalar meson field in the Waleckas MFA and in Chins RHA are quantized around the mean held. Its corrections on these theories are considered by perturbation up to the second order. The arbitrariness of makes us free to fix it at any stage in the calculation. When we fix it in the way of Waleckas MFA, the quantum corrections are big, and the result does not converge. When we fix it in the way of Chins RHA, the quantum correction is negligibly small, and the convergence is excellent. It shows that RHA covers the leading part of quantum field theory for nuclear systems and is an excellent zeroth order approximation for further quantum corrections, while the Waleckas MFA does not. We suggest to fix the parameter at the end of the whole calculation by minimizing the total energy per-nucleon for the nuclear matter or the total energy for the finite nucleus, to make the quantized relativistic mean field theory (QRMFT) a variational method.

Collapse of Entangled State and Entropy Increase in an Isolated System

We show that the collapse of the entangled quantum state makes the entropy increase in an isolated system. The second law of thermodynamics is thus proven in its most general form.

Statistical Separability of the World and Consistency Between Quantum Theory, Relativity, and Causality

We show that the quantum world with non-local states and original statistics is statistically separable. According to relativistic dynamics, the super-luminal signal transmission is impossible. The present quantum theory is therefore consistent with the relativity and the causality.