|Program name||Package id||Status||Status date|
|Package ID||Orig. computer||Test computer|
|NEA-0850/19||Linux-based PC,PC Windows||PC Windows|
ECIS-79 uses a sequential iteration method for solving the coupled differential equations arising in nuclear model calculations. It also performs parameter searches to fit calculated results to experimental data. It can be used for a range of models, e.g. first or second order harmonic or anharmonic vibrational model, symmetric or asymmetric rotational model, with a similar range of interaction potentials. It includes spin-orbit deformation.
ECIS-95 is a generalization of ECIS-79: for the rotational model vibrational bands are included. An option for solving the Dirac equation has been added. It also contains the statistical model including width fluctuation corrections as formulated by Peter Moldauer. Besides the use of Bessel expansion for form factors, the use of deformation lengths and the use of 'symmetrized' Woods-Saxon potentials, it includes:
two bound state transitions for particle-mode excitations with the possibility of the particle in the continuum
expression of cross sections in terms of Legendre polynomials
possibility of angular distribution for uncoupled states without giving explicitly all the reduced nuclear matrix elements
for Coulomb excitation, use of the magnetic multipole.
ECIS-06 - New version differs from previous version in the following features:
The whole program was converted to double-precision
In ECIS03 the dispersion relation as described by "C. MAHAUX AND R. SARTOR IN NUCL. PHYS A528 (1991) 253", is added to the real potencial, (it is a generalisation of the dispersion relation as described in "MAHAUX, C. and SARTOR, R., Nucl. Phys. A458 (1986) 25" already introduced in ECIS96 and 97).
Conversion of all FORMATS from Hollerith notation into 'quotes' notation.
ECIS06 is primarily ECIS03 modified for the use of a different relativistic 'reduced mass' in front of 'scalar' potentials, differing from the one used in front of Coulomb potentials. It is the application to coupled equations of the principles described in 'DWBA05' announced in the Workshop 'Perspectives on Nuclear Data in the Next Decade', on the 26-28/9/2005 at Bruyeres-le-Chatel, France.
Some generalisations have been introduced, in particular for the dispersion relation.
ECIS-12 - New version differs from previous version in the following features:
The possibility to fold the potentials with a Gauss, a Yukawa, or a Woods-Saxon was not verified in the ECIS codes after ECIS79. The purpose of ECIS12 is to verify it.
However, the concept of folding has been changed. In the previous versions, for the standard input of potentials, there were three sets of parameters (for real potentials, imaginary potentials and coulomb potentials), the choice was free for external input of potentials. For spin-orbit interaction with the Schroedinger equation V(r), two functions are needed, V1(r)=d/dr(V(r))/r and V2(r)=V(t)/r**2. In the previous versions, V1(r) and V2(r) where folded. In ECIS-12, only V(r) is. Also, charge distribution and not coulomb potentials can be folded in ECIS-12. Computation of derivatives has been changed from point by point computation to direct derivation.
For standard input of potentials, one or eight sets of folding parameters can be set. For external input of potentials, two new data are needed when they are given by points:
the line before radii and values
indication for spin-orbit potential if d/dr(V(r))/r is given,
indication for coulomb interaction if charge distribution or
Coulomb potential is given.
The address of each data is increased by one unit for each form factor read by points. Only charge densities can be folded. Coulomb potential and interactions related to it should be read in the same way.
The constants used in the calculations have been updated according to CODATA 2010. http://physics.nist.gov/cuu/Constants/Table/allascii.txt
atomic mass constant energy in MeV
CM=931.494061D0 instead of 931.4043D0 MEV/C**2
Planck constant over 2 pi times c in MeV fm
CHB=197.3269718D0 instead of 197.326968D0 MEV FM
inverse fine-structure constant
CZ=137.035999074D0 instead of 137.03599911D0 WITHOUT DIMENSION
but this change do not affect the results more than the use of different compilers.
The ECIS method is designed to solve sets of coupled differential equations when the coupling terms are not too strong. The iteration technique searches for the one required solution among the many which are mathematically possible.
The method supposes some ordering of the channels: first the ground state, then the state most strongly coupled to it. All channels must be coupled to some preceding one. The result of each iteration depends on this chosen order. If there is more than one equation related to the ground state the whole calculation must be repeated. The efficiency of the method is proportional to the ratio of the total number of equations to the number of those related to the ground state.
The usual methods can also be used, but the iteration method is compulsory for spin-orbit deformation and Dirac formalism.
|Package ID||Status date||Status|
|NEA-0850/19||17-DEC-2013||Tested at NEADB|
'Spin-orbit transition interactions', Physical Review C (Nuclear Physics), Phys. Rev. C 71, 057602 (2005)
Coupled Channel Formalism and ECIS Code.
Specialists'' Meeting on the Use of the Optical Model for the Calculation of Neutron Cross Sections Below 20 MeV, OECD/NEA 1986
J. M. Quesada, R. Capote, A. Molina, M. Lozano and J. Raynal:
"Analytical expressions for the dispersive contributions to the nucleon-nucleus optical potential", Physical Review C (Nuclear Physics), Phys. Rev. C 67, 067601 (2003) (3 pages)
Aspects Geometriques des Reactions. CEA-N-1529 (1972)
Optical-Model and Coupled-Channel Calculations in Nuclear Physics. 'International Atomic Energy Agency Report IAEA-SMR-9/8' pp. 281-322 (IAEA, Vienna, 1972) ICTP International Seminar Course: COMPUTING AS A LANGUAGE OF PHYSICS, Trieste, Italy, August 2-20 1971
Spin-Orbit Interaction in Inelastic Nucleon Scattering. 'THE STRUCTURE OF NUCLEI' 'International Atomic Energy Agency Report IAEA-SMR-9/9' pp. 75-116 (IAEA, Vienna, 1972) International Course on Nuclear Theory: "THE STRUCTURE OF NUCLEI", Trieste, Italy, January 13-March 12 1971
Recurrence Relations for Distorted-Wave Born Approximation Coulomb Exitation Integrals and their Use in Coupled Channel Calculations. Phys. Rev. C., Vol. 23, pp. 2571-2585 (June 1981)
Notes on ECIS-79 (May 25, 1982).
"Report on the International Nuclear Model Code Intercomparison: Coupled-Channel Model Study" January 1984 NEANDC-182A/INDC(NEA)3
|Package ID||Computer language|
Keywords: coupled channel theory, differential equations, nuclear models, statistical models.