| 1. |
- Alpkvist, Erik, et al.
(författare)
-
A new mathematical model for chemotactic bacterial colony growth
- 2004
-
Ingår i: Water Science and Technology. - : Biriwa Education Services. - 0273-1223 .- 1996-9732. ; 49:11-12, s. 187-192
-
Tidskriftsartikel (refereegranskat)abstract
- A new continuum model for the growth of a single species biofilm is proposed. The geometry of the biofilm is described by the interface between the biomass and the surrounding liquid. Nutrient transport is given by the solution of a semi-linear Poisson equation. In this model we study the morphology of a chemotactic bacterial colony, which grows in the direction of increasing nutrient concentration. Numerical simulations using the level set method and finite difference schemes are presented. The results show rich heterogeneous morphology.
|
|
| 2. |
|
|
| 3. |
- Bengtsson, Peter, et al.
(författare)
-
Energy structure and transition rates in the Ne-like sequence from relativistic CI calculations
- 2012
-
Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 128-128
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Atomic data are important in astrophysical applications and transition rates can be used in the determination of element abundances and plasma diagnostics. To provide for the extensive data needs a number of general computer codes such as SUPERSTRUCTURE, CIV3, and ATSP2K have been developed. As an alternative to these codes, which all rely on the Breit-Pauli approximation, the fully relativistic GRASP2K code can be used. GRASP2K is based on the multiconfiguration Dirac-Hartree-Fock method and implements a bi-orthogonal transformation method that permits initial and final states in a transition array to be optimized separately, which, in many cases, leads to more accurate values of the resulting rates. The GRASP2K package also contains modules to compute diagonal and off-diagonal hyperfine interaction constants, isotope shifts, Land´e gJ factors, and splittings of magnetic sub-state in intermediate and strong magnetic fields. In this work, GRASP2K has been applied to provide highly accurate spectroscopic data for ions in the Ne-like sequence between Mg III and Kr XXVII. Valence, core-valence, and core-core correlation effects were accounted for through SD-MR expansions to increasing sets of active orbitals. In Mg III, Al IV, Si V, P VI, S VII, and Ar IX, for which experimental energies are known to high accuracy, the mean error in the calculated energies is only 0.011%. For ions with no available experimental energy levels the calculated values should be most valuable in various applications. The high accuracy of the calculated energies makes it possible, in some cases, to to point out experimental values that are in error. Babushkin (length) and Coulomb (velocity) forms of transition rates are computed and agree to within a few percent for the majority of the allowed transitions. Computed lifetimes for states belonging to the 2p33s and 2p53d configurations are in good agreement with values from beam-foil measurements as well as from accurate MCHF Breit-Pauli calculations.
|
|
| 4. |
- Ekman, Jörgen, et al.
(författare)
-
Calculations with spectroscopic accuracy : energies, transition rates, and Landé g_J-factors in the carbon isoelectronic sequence from Ar XIII to Zn XXV
- 2014
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 564
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive self-consistent multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and subsequent relativistic configuration in- teraction calculations are performed for 262 states belonging to the 15 configurations 2s22p2, 2s2p3, 2p4, 2s22p3l, 2s2p23l, 2p33l and 2s22p4l (l = 0,1,2) in selected carbon-like ions from Ar XIII to Zn XXV. Electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with existing theoretical calculations and data from the Chianti and NIST databases. In addition, Landé gJ -factors and radiative electric dipole transition rates are given for all ions. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.
|
|
| 5. |
|
|
| 6. |
- Grumer, Jon, et al.
(författare)
-
Atomic Data and Stark Broadening Parameters for Sn II and Sn III
- 2013
-
Ingår i: Book of abstracts. - : Institute of Modern Physics, Chinese Academy of Sciences.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Synopsis Extensive multicon guration Dirac-Hartree-Fock (MCDHF) and relativistic con guration interaction (RCI) calculations of energies, transition rates and broadening parameters are reported for Sn II and Sn III, ions which are of importance for plasma modeling. Results are compared with other recent works.
|
|
| 7. |
- Gustafsson, Stefan, et al.
(författare)
-
Combining Multiconfiguration and Perturbation Methods : Perturbative Estimates of Core-Core Electron Correlation Contributions to Excitation Energies in Mg-Like Iron
- 2017
-
Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- Large configuration interaction (CI) calculations can be performed if part of the interaction is treated perturbatively. To evaluate the combined CI and perturbative method, we compute excitation energies for the states in Mg-like iron. Starting from a CI calculation including valence and core-valence correlation effects, it is found that the perturbative inclusion of core-core electron correlation halves the mean relative differences between calculated and observed excitation energies. The effect of the core-core electron correlation is largest for the more excited states. The final relative differences between calculated and observed excitation energies is 0.023%, which is small enough for the calculated energies to be of direct use in line identifications in astrophysical and laboratory spectra.
|
|
| 8. |
- Gustafsson, Stefan, et al.
(författare)
-
MCDHF and RCI calculations of energy levels, lifetimes and transition rates for 3l3l ', 3l4l ', and 3s5l states in Ca IX - As XXII and Kr XXV
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597:A76
-
Tidskriftsartikel (refereegranskat)abstract
- Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations were performed for states of the 3l3l 0, 3l4l 0 and 3s5l configurations in the Mg-like ions Ca IX - As XXII and KrXXV. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated excitation energies are in very good agreement with observations for the lowest levels. For higher lying levels observations are often missing and present energies aid line identification in spectra. Lifetimes and transition data are given for all ions. There is an excellent agreement for both lifetimes and transition data with recent multiconfiguration Hartree-Fock Breit Pauli calculations.
|
|
| 9. |
- Jönsson, Per, et al.
(författare)
-
A program for computing weak and intermediate field Zemman splittings from MCHF wave functions
- 2002
-
Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 144:2, s. 188-199
-
Tidskriftsartikel (refereegranskat)abstract
- Given electronic wave functions generated by the MCHF_CI program (LSJ format), this program calculates diagonal Landé g factors that determine separations of magnetic sublevels in weak external magnetic fields. In addition the program computes off-diagonal Landé g factors and constructs the total interaction matrix for an atom in a magnetic field. By diagonalizing the interaction matrix and plotting the eigenvalues as functions of the magnetic field, Zeeman structures beyond the weak field limit are obtained.
|
|
| 10. |
- Jönsson, Per, et al.
(författare)
-
Energy levels and transition rates for the boron isoelectronic sequence : Si X, Ti XVIII – Cu XXV
- 2013
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 559
-
Tidskriftsartikel (refereegranskat)abstract
- Relativistic configuration interaction (RCI) calculations are performed for 291 states belonging to the configurations 1s22s22p, 1s22s2p2, 1s22p3, 1s22s23l, 1s22s2p3l, 1s22p23l, 1s22s24l , 1s22s2p4l , and 1s22p24l (l = 0, 1,2 and l = 0, 1, 2, 3) in boron-like ions Si X and Ti XVIII to Cu XXV. Electron correlation effects are represented in the wave functions by large configuration state function (CSF) expansions. States are transformed from j j-coupling to LS -coupling, and the LS -percentage compositions are used for labeling the levels. Radiative electric dipole transition rates are given for all ions, leading to massive data sets. Calculated energy levels are compared with other theoretical predictions and crosschecked against the Chianti database, NIST recommended values, and other observations. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.
|
|
