NLOM — a program for nonlocal optical model calculations

R-matrix method and the nonlocal nucleon optical potential

“…The comparison of the OM results given by the calculable R-matrix method [15] with those given by the three other methods [17][18][19] confirms that the calculable R-matrix method is an efficient, alternative method to treat the nonlocality of the nucleon OP. The direct evaluation of the nonlocal term of the OP based on the Lagrange-mesh method can be applied further in the OM study using the microscopic nucleon OP given by the folding model calculation that treats the nonlocal exchange term exactly [5].…”

“…In the study of the nucleon transfer reactions by Titus et al [18,21], the iterative method has been used to determine both the scattering and bound nucleon wave functions (the code NLAT). The NLOM method [10,17] was suggested to solve the nonlocal OM equation quickly and reliably, using the Green-function transformation to convert the scattering wave function to the form of a bound-state wave function that can be expanded over an orthonormal basis. Then the main problem is to solve a set of the inhomogeneous linear equations using, e.g., the Lanczos method which also needs an iterative procedure.…”

“…For the nonlocal nucleon OP, we have chosen the PB [9] and TPM [12] potentials as well as the energydependent nonlocal OP by Lovell et al [13,14] to study the elastic nucleon scattering on 27 Al, 40 Ca, 48 Ca, 90 Zr, and 208 Pb targets at energies of 14.6 MeV to 40 MeV. The OM results obtained with the calculable R-matrix method are compared with those obtained with other methods given by the computer codes NLOM [10,17], NLAT [18], and DWBA98 [19].…”

R-matrix method and the nonlocal nucleon optical potential

“…The NLOM method [10,17] was suggested to solve the nonlocal OM equation quickly and reliably, using the Green-function transformation to convert the scattering wave function to the form of a bound-state wave function that can be expanded over an orthonormal basis. Then the main problem is to solve a set of the inhomogeneous linear equations using, e.g., the Lanczos method which also needs an iterative procedure.…”

Singular Value Decomposition Solution of the Schrödinger Equation in the Presence of Exchange Terms

“…We have shown that it is a definite improvement over the conventional iteration techniques. Other methods have been developed which consist in introducing a set of basis functions such as Laguerre polynomials, and expanding both the solution and the target states into this basis [1,2,4,7,10,12,14,17]. Another such expansion that is widely used and accurate is known as the Moments Method [3,8,9,11,13,15,16] which uses a set of basis functions obtained by applying successively higher powers of the Hamiltonian operator with local potentials on an initial scattering wave function.…”