**RSICC CODE PACKAGE PSR-546**

** **

**1. NAME AND TITLE: **

DWUCK-CHUCK: Nuclear Model Code System for Distorted Wave Born

Approximation and Coupled Channel Calculations.

**2. CONTRIBUTOR**

University of Colorado, Boulder, Colorado.

**3. CODING LANGUAGE AND
COMPUTER**

Fortran 77; VAX and PC (P00546MNYCP00).

**4. NATURE OF PROBLEM
SOLVED**

This package contains DWUCK-4, DWUCK-5 and CHUCK-3. The program DWUCK calculates the scattering differential cross section. The incoming and outgoing waves may be in any combination of spin 0, 1/2 or 1 particles.

The program CHUCK3 can be used for coupled-channel calculations to evaluate nuclear scattering amplitudes and differential collision cross sections. The code calculates nuclear reaction cross sections by numerically solving an appropriate set of coupled equations. This treatment differs from that of the distorted wave Born approximation (DWBA) program DWUCK4, which solves the scattering problem to first order only in the interaction potential. The solution to the set of coupled equations; however, solves the problem to all orders in the interaction potential. The program CHUCK3 can be run with a one way coupling from the initial state channels to the final state channels (no back coupling) to give the same result as the DWBA program DWUCK4. Both non-relativistic and relativistic kinematics is available. An effort has been made in this program to keep the input data for CHUCK3 in a form as similar as feasible to the DWBA code DWUCK4.

The codes were first developed in the 1970’s. RSICC originally packaged the VAX version in 1986 as PSR-235. This PSR-546 package includes files which the author updated to run on PC under Windows.

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**5. METHOD OF SOLUTION**

For DWUCK-4 the general form of the distorted wave
Born approximation (DWBA) is used. The spin dependent parts of the optical
potentials for the distorted waves must be diagonal in the total and orbital
angular momentum. The calculations are per- formed in a zero range form between
the coordinates of the incoming and outgoing waves. The particle transfer
reactions can be treated with a local energy approximation for the finite range
effects.

DWUCK-5 is the finite range version of DWUCK-4. The full finite
range is calculated with the momentum expansion technique due to Lowell
Charlton.

CHUCK-3 differs from the distorted wave Born approximation (DWBA) which uses the T-matrix approach in the sense that while in DWBA the approach is equivalent to the solution of a set of (two) coupled equations with coupling one way from the initial (elastic) to the final outgoing channel, in the coupled channel approach the coupling is two ways. The two way coupling can affect the distorted waves in both channels and, therefore, the final amplitudes in a non-linear fashion.

**6. RESTRICTIONS OR
LIMITATIONS**

Reactions such as heavy particle stripping and knock-on reactions cannot be calculated with DWUCK-4 since the finite range effects are important. For finite range effects DWUCK-5 should be used which has a limit of 200 partial waves, 400 integration steps and 40 expansion coefficients for each distorted wave.

Number of partial waves less or equal to 50.

Number of intrinsic channels (including elastic) less than or equal to 8.

**7. TYPICAL RUNNING TIME**

Not noted.

**8. COMPUTER HARDWARE
REQUIREMENTS**

The codes run on PC or VAX computers.

**9. COMPUTER SOFTWARE
REQUIREMENTS**

The included PC executables were created by the author with MS Fortran version 5.0. RSICC made no changes to the package but tested on the executables on a Pentium computer running Windows XP and Windows Vista. RSICC also compiled successfully under Windows using Compaq Visual Fortran 6.6C and on an AMD Opteron running Red Hat Enterprise Linux 4 with pgf95 vers 6.1-6.

**10. REFERENCES**

**a. included documentation**

P.D. Kunz, “Coupled Channels Program” for CHUCK.

P. D. Kunz, “Zero Range Distorted Wave Born Approximation” for DWUCK-4.

P. D. Kunz, Description of DWUCK-5.

**b. background information**

E. Sartori, "Report on the International Nuclear Model Code Intercomparison: Coupled-Channel Model Study," NEANDC-182A/INDC(NEA) (January 1984).

**11. CONTENTS OF CODE
PACKAGE**

The package is transmitted on a CD in a Winzip file which includes the referenced documentats listed above in 10.a, the source code, 16-bit and 32-bit Windows PC executables, and test cases.

**12. DATE OF ABSTRACT**

June 2008.

**KEYWORD:** NUCLEAR
MODELS