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Manuscript Title: RIS3: a program for relativistic isotope shift calculations
Authors: C. Nazé, E. Gaidamauskas, G. Gaigalas, M. Godefroid, P. Jönsson
Program title: RIS3
Catalogue identifier: ADEK_v2_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 184(2013)2187
Programming language: Fortran 77.
Computer: HP ProLiant BL465c G7 CTO.
Operating system: Centos 5.5, which is a Linux distribution compatible with Red Hat Enterprise Advanced Server.
Keywords: Isotope shift, Field shift, Mass shift, Normal mass shift, Specific mass shift, Relativistic nuclear recoil, Nuclear radius.
Classification: 2.1.

Subprograms used:
Cat Id Title Reference
ADZL_v1_1 GRASP2K VERSION 1_1 CPC 184(2013)2197

Does the new version supersede the previous version?: Yes

Nature of problem:
Prediction of level and transition isotope shifts in atoms using four-component relativistic wave functions.

Solution method:
The nuclear motion and volume effects are treated in first order perturbation theory. Taking the zero-order wave function in terms of a configuration state expansion |ΨPJMJ 〉 = Σμcμ |Φ(γμPJMj)〉, where P, J and MJ are, respectively, the parity and angular quantum numbers, the electron density at the nucleus and the normal and specific mass shift parameters may generally be expressed as Σμ,νcμcν〈γμPJMj|V|γνPJMj〉 where V is the relevant operator. The matrix elements, in turn, can be expressed as sums over radial integrals multiplied by angular coefficients. All the angular coefficients are calculated using routines from GRASP2K version 1_1 package [1].

Reasons for new version:
This new version takes the nuclear recoil corrections into account within the (αZ)4m2/M approximation [2] and also allows a storage of the angular coefficients for a series of calculations within a given isoelectronic sequence. Furthermore, the program JJ2LSJ, a module of GRASP2K version 1_1 toolkit that allows a transformation of ASFs from a jj-coupled CSF basis into an LSJ-coupled CSF basis, has been especially adapted to present RIS3 results using LSJ labels of the states. This additional tool is called RIS3_LSJ.

Summary of revisions:
This version is compatible with the new angular approach of GRASP2K version 1_1 package [1] and can store necessary angular coefficients. According to the formalism of the relativistic nuclear recoil, the "uncorrected" expression of the normal mass shift has been fundamentally modified compared with its expression in [3].

The complexity of the cases that can be handled is entirely determined by the GRASP2K package [1] used for the generation of the electronic wave functions.

Unusual features:
Angular data is stored on disc and can be reused. LSJ labels are used for the states.

Running time:
As an example, we evaluated the isotope shifts parameters and the electron density at the origin using the wave functions of Be-like system. We used MCDHF wave function built on a complete active space (CAS) with n = 8 (296 626 CSFs - 62 orbitals) that contains 3 non-interacting blocks of given parity and J values involving 6 different eigenvalues in total. Calculations take around 10 hours on one AMD Opteron 6100 @ 2.3GHz CPU with 8 cores (64GB DDR3 RAM 1.333GHz). If angular files are available the time is reduced to 20 minutes. The storage of the angular data takes 139Mb and 7.2Gb for the one-body and the two-body elements, respectively.

[1] P. Jönsson, G. Gaigalas, J. Bieron, C. Froese Fischer, I. Grant, Comput. Phys. Commun. (2012) submitted.
[2] E. Gaidamauskas, C. Nazé, P. Rynkun, G. Gaigalas, P. Jönsson, M. Godefroid, J. Phys. B: At. Mol. Opt. Phys. 44 (17) (2011) 175003.
[3] P. Jönsson, C. Froese Fischer, Comput. Phys. Commun. 100 (1997) 81-92.