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A renewed version of the computer code GAMOW (Vertse et al., 1982) is given in which the difficulties in calculating broad neutron resonances are amended. New types of phenomenological neutron potentials with strict finite range are built in. Landscape of the S -matrix can be generated on a given domain of the complex wave number plane and S -matrix poles in the domain are localized. Normalized Gamow wave functions and trajectories of given poles can be calculated optionally. 1 Program summary Program Title: JOZSO Program Files doi: http://dx.doi.org/10.17632/gh2rfnzn58.1 Licensing provisions: GPLv3 Programming language: Fortran 90 Supplementary material: A readme file: https://github.com/czylabsonasa/jozso Nature of problem: The program calculates the poles of the partial wave S -matrix for spherically symmetric strictly finite range complex potentials. A few types of potential forms are built in and option for reading in external potential form is given. Landscape of the S -matrix on a given domain of the complex wave number plane can be calculated. Accurate position of the poles can be determined. Normalized Gamow wave functions and trajectories of given poles can be calculated optionally. Solution method: Internal and external solutions satisfying boundary conditions in the origin and in the asymptotic region are generated by integrating the radial equation with adaptive step-size control for Runge–Kutta method. The difference of the logarithmic derivatives is calculated for a range of distances. The minimum of the summed modulus of the differences is searched using the Nelder–Mead algorithm. Pole trajectories and normalized Gamow functions can be calculated optionally. Additional comments including Restrictions and Unusual features: The region of interest is restricted to the lower half of the wave number plane. Pole solutions from the upper half wave number plane can be safely computed by using the codes GAMOW [1] ANTI [2]. References: [1] T. Vertse, K. F. Pal, Z. Balogh, Computer Physics Communications 27, 309 (1982). [2] L.Gr. Ixaru, M. Rizea, T. Vertse, Computer Physics Communications 85, 217 (1995).

Cutting off the tail of the Woods–Saxon (WS) and generalized WS (GWS) potentials changes the distribution of the poles of the [Formula: see text]-matrix considerably. Here, we modify the tail of the cut-off WS (CWS) and cut-off generalized WS (CGWS) potentials by attaching Hermite polynomial tails to them beyond the cut. The tails reach the zero value more or less smoothly at the finite ranges of the potential. Reflections of the resonant wave functions can take place at different distances. The starting points of the pole trajectories have been reproduced not only for the real values and the moduli of the starting points, but also for the imaginary parts.

The classical square well potential is smoothed with a finite range smoothing function in order to get a new simple strictly finite range form for the phenomenological nuclear potential. The smoothed square well form becomes exactly zero smoothly at a finite distance, in contrast to the Woods-Saxon form. If the smoothing range is four times the diffuseness of the Woods-Saxon shape both the central and the spin-orbit terms of the Woods-Saxon shape are reproduced reasonably well. The bound single particle energies in a Woods-Saxon potential can be well reproduced with those in the smoothed square well potential. The same is true for the complex energies of the narrow resonances., Comment: 2 fig

The real Scarf II potential is discussed as a radial problem. This potential has been studied extensively as a one-dimensional problem, and now these results are used to construct its bound and resonance solutions for $l=0$ by setting the origin at some arbitrary value of the coordinate. The solutions with appropriate boundary conditions are composed as the linear combination of the two independent solutions of the Schr\"odinger equation. The asymptotic expression of these solutions is used to construct the $S_0(k)$ s-wave $S$-matrix, the poles of which supply the $k$ values corresponding to the bound, resonance and anti-bound solutions. The location of the discrete energy eigenvalues is analyzed, and the relation of the solutions of the radial and one-dimensional Scarf II potentials is discussed. It is shown that the generalized Woods--Saxon potential can be generated from the Rosen--Morse II potential in the same way as the radial Scarf II potential is obtained from its one-dimensional correspondent. Based on this analogy, possible applications are also pointed out., Comment: 3 figs

Cutting of the tail of the Woods–Saxon (WS) potential influences the distribution of the poles of the [Formula: see text]-matrix considerably. A new attempt is made here to correct the tail of the cut-off WS potential in order to bring the positions of the poles closer to the WS potential without cut. New types of strictly finite range potentials are introduced in which the tail of the WS and the generalized Woods–Saxon (GWS) potentials are modified to damp them at their ends. This damping affects the energies of the bound and narrow resonant states weakly. The resonant pole positions in the new potentials were affected more significantly and the new pole positions became closer to that of the GWS potential without cut. However, the cut-off effect cannot be diminished completely. The new potentials belong to the [Formula: see text] function class.

The positions of the $l=0$ $S$-matrix poles are calculated in generalized Woods-Saxon (GWS) potential and in cut-off generalized Woods-Saxon (CGWS) potential. The solutions of the radial equations are calculated numerically for the CGWS potential and analytically for GWS using the formalism of Gy. Bencze \cite{[Be66]}. We calculate CGWS and GWS cases at small non-zero values of the diffuseness in order to approach the square well potential and to be able to separate effects of the radius parameter and the cut-off radius parameter. In the case of the GWS potential the wave functions are reflected at the nuclear radius therefore the distances of the resonant poles depend on the radius parameter of the potential. In CGWS potential the wave function can be reflected at larger distance where the potential is cut to zero and the derivative of the potential does not exist. The positions of most of the resonant poles do depend strongly on the cut-off radius of the potential, which is an unphysical parameter. Only the positions of the few narrow resonances in potentials with barrier are not sensitive to the cut-off distance. For the broad resonances the effect of the cut-off can not be corrected by using a suggested analytical form of the first order perturbation correction., Comment: Accepted by Nucl. Phys. A

One- and two-quasi particle states are studied in the complex energy plane. It is found that the pairing interaction does not change the character of the complex state. If a normal state is a physi ...

In a cut-off Woods-Saxon (CWS) potential with realistic depth $S$-matrix poles being far from the imaginary wave number axis form a sequence where the distances of the consecutive resonances are inversely proportional with the cut-off radius value, which is an unphysical parameter. Other poles lying closer to the imaginary wave number axis might have trajectories with irregular shapes as the depth of the potential increases. Poles being close repel each other, and their repulsion is responsible for the changes of the directions of the corresponding trajectories. The repulsion might cause that certain resonances become antibound and later resonances again when they collide on the imaginary axis. The interaction is extremely sensitive to the cut-off radius value, which is an apparent handicap of the CWS potential., 5 pages, 3 figures

Processes occurring in the continuum part of the spectrum are described by using a basis consisting of bound and antibound states plus Gamow resonances and the continuum background. The calculations, performed in the complex energy plane, are applied to the study of weakly bound nuclei. The influence of antibound states upon physical quantities in halo nuclei is assessed.

A formalism to evaluate the resonant states produced by two particles moving outside a closed shell core is presented. The two-particle states are calculated by using a single-particle representation consisting of bound states, Gamow resonances and scattering states in the complex energy plane (Berggren representation). Two representative cases are analysed corresponding to whether the Fermi level is below or above the continuum threshold. It is found that long-lived resonances are mostly determined by either bound states or by narrow Gamow resonances. However, they are significantly affected by wide resonances and the continuum background itself.

The theory of the superheavy elements is reviewed with the main focus on nuclear structure aspects. The structure of the odd- N superheavy elements is investigated using a variety of self-consistent approaches. Microscopic shell corrections, extracted from Skyrme–Hartree–Fock and relativistic mean-field calculations, elucidate the question of the centre-of-shell-stability in the superheavy region. Finally, the existence of exotic configurations, having gross non-uniformities of nucleonic density, expected to occur in nuclei with very large atomic numbers, is addressed.

Strictly finite-range (SFR) potentials are exactly zero beyond their finite range. Single-particle energies and densities as well as S-matrix pole trajectories are studied in a few SFR potentials suited for the description of neutrons interacting with light and heavy nuclei. The SFR potentials considered are the standard cut-off Woods--Saxon (CWS) potentials and two potentials approaching zero smoothly: the SV potential introduced by Salamon and Vertse and the SS potential of Sahu and Sahu. The parameters of these latter were set so that the potentials may be similar to the CWS shape. The range of the SV and SS potentials scales with the cube root of the mass number of the core like the nuclear radius itself. For light nuclei a single term of the SV potential (with a single parameter) is enough for a good description of the neutron-nucleus interaction. The trajectories are compared with a bench-mark for which the starting points (belonging to potential depth zero) can be determined independently. Even the CWS potential is found to conform to this bench-mark if the range is identified with the cutoff radius. For the CWS potentials some trajectories show irregular shapes, while for the SV and SS potentials all trajectories behave regularly., 14 figs

The coupled-channel Schrodinger equation with outgoing wave boundary conditions is employed to study the fine structure seen in the proton decay of deformed even-N, odd-Z rare earth nuclei 131-Eu and 141-Ho. Experimental lifetimes and proton-decay branching ratios are reproduced. The comparison with the standard adiabatic theory is made., 4 pages, 2 figures submitted to Phys. Rev. Lett

Temperature dependent shell corrections are calculated taking into account the continuum spectrum of a finite depth mean field potential. The effect of the continuum is split up into a discret term which includes Gamow resonances and an integral along a contour in the complex energy plane. The resonances appear in the formalism in the same manner as bound states and at low temperatures they give the main part of the contribution due to the continuum. The method is applied to the particular case of {sup 208}Pb. The temperature for which the shell corrections are washed out completly is estimated at T{approx}2.5 MeV. {copyright} {ital 1997} {ital The American Physical Society}

Energies, sum rules and partial decay widths of giant resonances are calculated solving exactly the continuum RPA equations corresponding to a central Woods-Saxon potential. An approximated treatment of those quantities in terms of pole expansions of the Green function is also performed. It is found that the approximated results agree well with the exact ones. The expansions allow one to understand the microscopic structure of the resonances. Comparison with experimental data is made and a search for physically meaningful resonances is carried out.

To avoid instability problems in calculating anti-bound and resonant solutions, we propose to represent the wave-function with the sum of its large distance asymptotic form and a numerically calculated correction function. The resulting inhomogeneous equation is stable, therefore it can be solved accurately with standard methods.

It is shown that the piecewise perturbation methods provide a powerful numerical tool for solving the complex eigenvalue problem of the Schrodinger equation in a complex optical potential. One of them, the CPM(2), is compared with the existing NAG subroutines and found substantially faster. We also present appropriate methods to compute the solution in the vicinity of the origin and in the asymptotic region.

The motions of the l = 0 poles of the S-matrix with varying potential strength is calculated in a cut-off Woods-Saxon (CWS) potential and in the Salamon-Vertse (SV) potential [3]. Both potentials are zero beyond a certain finite distance but the CWS potential has a jump at the cut while the SV potential goes to zero smoothly. The jump of the CWS potential might cause a strange circling of the trajectories at their starting region. This feature does not appear with the SV potential. Starting points of the trajectories depend on the ranges of the potentials. For CWS these points do depend on the unphysical cut-off radius. In this respect the SV potential seems to be superior to the CWS potential.

Energies of the S-matrix poles are calculated by solving the radial Schroedinger equation numerically by using Ixaru's CPM(2) method. The trajectories of the poles in the complex wave number plane are determined for two nuclear potentials that are zero beyond finite distances. These are the Woods-Saxon form with cutoff and the Salamon-Vertse potential, which goes to zero smoothly at a finite distance[1]. Properties of the trajectories are analyzed for real and complex values of the depths of the corresponding potentials.

It is shown that the set of bound states and single-pa tide esonances consisting of the outgoing solutions of the Schodinge equation can be used as a ep esentation to describe p ocesses taking place in the continuum part of nuclear spectra. This is the first thoough investigation of completeness properties using realistic nuclear wave functions.

The trajectories of $S$-matrix poles are calculated in the finite-range phenomenological potential introduced recently by Salamon and Vertse [Phys. Rev. C 77, 037302 (2008)] (SV). The potential is similar to a Woods-Saxon (WS) interaction, but it is exactly zero beyond a radius, without any cutoff. The trajectories of the resonance poles in this SV potential are compared to the corresponding trajectories in a cutoff WS potential for $lg0$. The dependence on the cutoff radius is demonstrated. The starting points of the trajectories turn out to be related to the average ranges of the two terms in the SV potential.

Partial decay widths of the giant monopole resonance in 208 Pb are calculated within the continuum RPA exactly, i.e. without any further approximation in a Woods-Saxon plus Coulomb potential and using a separable residual interaction. The giant monopole resonance is fragmented. The averaged widths and branching ratios are compared with other calculations and with available experimental data.

A new method is presented for the calculation of the shell correction with the inclusion of the continuum part of the spectrum. The smoothing function used has a finite energy range in contrast to the Gaussian shape of the Strutinski method. The new method is especially useful for light nuclei where the generalized Strutinski procedure cannot be applied.

The influence of thermal fluctuations upon escape widths of giant resonances is analyzed within a thermal random phase approximation that includes the effect of the continuum through the use of resonant single-particle states in the basis set of states. It is found that those escape widths are only weakly dependent on the temperature.

Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.

This work reviews foundations and applications of the complex-energy continuum shell model that provides a consistent many-body description of bound states, resonances, and scattering states. The model can be considered a quasi-stationary open quantum system extension of the standard configuration interaction approach for well-bound (closed) systems., Topical Review, J. Phys. G, Nucl. Part. Phys, in press (2008)

Particle-hole partial decay widths are calculated within the continuum RPA exactly, i.e. without any further approximation, in a square well plus Coulomb potential and using a separable residual interaction. The results are compared with the ones obtained by making pole expansion of the single-particle Green functions (Berggren and Mittag-Leffler). It is found that the Berggren and Mittag-Leffler expansion give results in good agreement with the “exact” ones.

The inclusion of single particle Gamow functions as building blocks in nuclear calculations is presented here through three different examples. We show that it is a quick method which enables us to account for the most important features of the continuum effect.

A simple form for phenomenological nuclear potential is introduced as an alternative to the popular Woods-Saxon (WS) form. In contrast to the WS form the new form becomes exactly zero at a finite distance and all derivatives of this form are continuous everywhere. The sequence of the single-particle levels of a WS potential with realistic parameters can be reproduced reasonably well with the new potential in which even the positions of the broad resonances are free from uncertainties.

The parameters of the nuclear liquid drop model, such as the volume, surface, symmetry, and curvature constants, as well as bulk radii, are extracted from the non-relativistic and relativistic energy density functionals used in microscopic calculations for finite nuclei. The microscopic liquid drop energy, obtained self-consistently for a large sample of finite, spherical nuclei, has been expanded in terms of powers of A^{-1/3} (or inverse nuclear radius) and the isospin excess (or neutron-to-proton asymmetry). In order to perform a reliable extrapolation in the inverse radius, the calculations have been carried out for nuclei with huge numbers of nucleons, of the order of 10^6. The Coulomb interaction has been ignored to be able to approach nuclei of arbitrary sizes and to avoid radial instabilities characteristic of systems with very large atomic numbers. The main contribution to the fluctuating part of the binding energy has been removed using the Green's function method to calculate the shell correction. The limitations of applying the leptodermous expansion to actual nuclei are discussed. While the leading terms in the macroscopic energy expansion can be extracted very precisely, the higher-order, isospin-dependent terms are prone to large uncertainties due to finite-size effects., Comment: 13 pages revtex4, 7 eps figures, submitted to Phys. Rev. C

An unified shell model scheme to evaluate simultaneously the contributions of bound single-particle states, Gamow resonances, antibound (virtual) states and continuum complex scattering states is presented. The formalism could be very suitable to study processes occurring in the continuum part of the nuclear spectra.

We show how calculate the energies and the widths of quasiparticle resonant states without solving the complex bcs equations. The method is based on BCS equations solved in the real representation including the continuum. In this representation the quasiparticle resonances are associated to the Gamow states of the mean field.

We present a simple method for calculating the energies and the widths of quasiparticle resonant states. The method is based on BCS equations solved in the Berggren representation. In this representation the quasiparticle resonances are associated to the Gamow states of the mean field. The method is illustrated for the case of neutron-rich nuclei $^{20-22}$O and $^{84}$Ni. It is shown that the contribution of the continuum coupling to the pairing correlations is small and largely dominated by a few resonant states close to the continuum threshold., Comment: 14 pages, 2 figures

A generalization of the complex shell model formalism is presented that includes antibound states in the basis. These states, together with bound states, Gamow states, and the continuum background, represented by properly chosen scattering waves, form a representation in which all states are treated on the same footing. Two-particle states are evaluated within this formalism, and observable two-particle resonances are defined. The formalism is illustrated in the well-known case of $^{11}\mathrm{Li}$ in its bound ground state and in $^{70}\mathrm{Ca}$(g.s.), which is also bound. Both cases are found to have a halo structure. These halo structures are described within the generalized complex shell model. We investigated the formation of two-particle resonances in these nuclei, but no evidence of such resonances was found.

A new unified shell model scheme is introduced in which the single particle basis is a generalization of the Berggren representation. This repesentation includes virtual i.e. antibound basis states as well. We apply the new scheme to the ground state of the exotic nucleus 11Li. Here the antibound pole and the complex continuum both have large contributions and neither of them can be neglected.

The study of giant resonances in nuclei is attracting much attention both experimentally and theoretically @1,2#. The importance of these studies is that they may provide information about the continuum part of nuclear spectra as well as an understanding of the nuclear dynamics in the continuum. However, there is not much experimental evidence regarding partial decay widths from giant resonances—even the theoretical results are scarce. The reason for this is that the processes of formation and decay of giant resonances are time dependent and a proper treatment of such processes is a very difficult task. Experimentally, it is not easy to subtract the interesting signals from the background. Moreover, if the resonance is not isolated what one measures is not related to the resonance itself but rather to the result of the contribution of all the overlapping resonances, including their interference. The relativistic random-phase approximation ~RRPA !@ 3 # is a natural extension of the random-phase approximation ~RPA! which allows for the treatment of particle-hole states in the continuum. The eigenvalues of the RRPA can be complex due to the admixture of bound and resonant states in the unperturbed particle-hole basis ~Berggren’s representation !. The imaginary part of a complex eigenvalue is associated with the escape width of the state @4#. The formalism has been presented in detail previously and several applications of it have been given, particularly for the description of charge-conserving multipole excitations in 208 Pb @7#. As has been discussed in @4# the residues of the S matrix at a complex energy v n are the partial decay widths of the resonance n if the resonance is isolated ~nonoverlapping!. For such a resonance there exists a direct correspondence between the total escape width and the imaginary part of the energy, i.e., G n522Im(v n). This result has been confirmed for the case of the decay of the giant monopole resonance in 208 Pb @7# .I n the present case we shall show that similar results are also valid for charge-exchange modes, i.e., the isobaric analog ~IAS! and Gamow-Teller giant resonances ~GTGR’s! in 208 Bi.

An evaluation of two-particle resonances in the complex energy plane is presented. The representation used in the method consists of bound and antibound single-particle states, Gamow resonances and scattering waves on the complex energy plane. Within this representation the structure of halo nuclei is studied.

One-body quantum tunneling to continuum is treated via the two-potential approach, dividing the tunneling potential into external and internal parts. We show that corrections to this approach can be minimized by taking the separation radius inside the interval determined by simple expressions. The resulting two-potential approach reproduces the resonance energy and its width, both for narrow and wide resonances. We also demonstrate that, without losing its accuracy, the two-potential approach can be modified to a form resembling the R-matrix theory, yet without any uncertainties of the latter related to the choice of the matching radius., 7 two-column pages, 3 figures, extra-explanation added, Phys. Rev. A, in press

The mass A = 140 products of the 54Fe (315 MeV) + 92Mo reaction were selected by a recoil mass spectrometer and studied in a recoil ‐ delayed γ‐γ coincidence experiment. A new 7 μs isomer was identified in the drip line nucleus 140Dy. Five cascading γ transitions were assigned to the decay of the Iπ = 8− {v9/2−[514] ⊗ v7/2+[404]} K isomer via the ground state band transitions. The established structure of 140Dy is discussed with reference to the fine structure in proton decay of 141Ho.

A new $7 \ensuremath{\mu}\mathrm{s}$ isomer in the drip line nucleus ${}^{140}\mathrm{Dy}$ was selected from the products of the ${}^{54}\mathrm{Fe}$ $(315 \mathrm{MeV}{)+}^{92}\mathrm{Mo}$ reaction by a recoil mass spectrometer and studied with recoil-delayed $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences. Five cascading $\ensuremath{\gamma}$ transitions were interpreted as the decay of an ${I}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ ${\ensuremath{\nu}{9/2}^{\ensuremath{-}}[514]\ensuremath{\bigotimes}\ensuremath{\nu}{7/2}^{+}[404]}$ K isomer $({T}_{1/2}=7.0(5) \ensuremath{\mu}\mathrm{s})$ via the ground-state band. The probability of proton emission from ${}^{141}\mathrm{Ho}$ to the ${0}^{+}$ ground state and to the ${2}^{+}$ excited state in ${}^{140}\mathrm{Dy}$ is discussed.

A formalism to evaluate the resonant states produced by two particles moving outside a closed shell core is presented. The two particle states are calculated by using a single particle representation consisting of bound states, Gamow resonances and scattering states in the complex energy plane (Berggren representation). Two representative cases are analysed corresponding to whether the Fermi level is below or above the continuum threshold. It is found that long lived two-body states (including bound states) are mostly determined by either bound single-particle states or by narrow Gamow resonances. However, they can be significantly affected by the continuum part of the spectrum., Comment: 11 pages, 4 figures

Our aim is to descibe proton emission from a deformed nucleus in a microscopic way. In our model, we assume that the shapes of the parent and the daughter nuclei are the same, and that both nuclei perform collective rotation. The parent state is constructed from collective states of a rotating core and single-proton wave functions. It is assumed that the proton moves in a quasi-bound state of an axially symmetric deformed potential. In the asymptotic region, the behavior of the proton wave function is governed by the Q p value of proton decay.

Alpha clustering is analyzed within a shell-model-like Berggren representation which includes the bound and outgoing single-particle resonant states of a realistic Woods-Saxon potential. It is found that the clustering of the alpha particle in $^{212}\mathrm{Po}$, leading to \ensuremath{\alpha} decay, can be described even for distances which are well beyond the surface of the daughter nucleus.

Pairing correlations for excited nuclei near the proton drip line are described by using finite-temperature BCS equations including the continuum part of the spectrum. The suitability of the proposed method to obtain stable solutions in the presence of single-particle resonances is shown.

The newly developed nonadiabatic method based on the coupled-channel Schroedinger equation with Gamow states is used to study the phenomenon of proton radioactivity. The new method, adopting the weak coupling regime of the particle-plus-rotor model, allows for the inclusion of excitations in the daughter nucleus. This can lead to rather different predictions for lifetimes and branching ratios as compared to the standard adiabatic approximation corresponding to the strong coupling scheme. Calculations are performed for several experimentally seen, non-spherical nuclei beyond the proton dripline. By comparing theory and experiment, we are able to characterize the angular momentum content of the observed narrow resonance., 12 pages including 10 figures

Shell corrections of the finite deformed Woods-Saxon potential are calculated using the Green's function method and the generalized Strutinsky smoothing procedure. They are compared with the results of the standard prescription which are affected by the spurious contribution from the unphysical particle gas. In the new method, the shell correction approaches the exact limit provided that the dimension of the single-particle (harmonic oscillator) basis is sufficiently large. For spherical potentials, the present method is faster than the exact one in which the contribution from the particle continuum states is explicitly calculated. For deformed potentials, the Green's function method offers a practical and reliable way of calculating shell corrections for weakly bound nuclei., Comment: submitted to Phys. Rev. C, 12 pages, 7 figures

Shell corrections to the nuclear binding energy as a measure of shell effects in superheavy nuclei are studied within the self-consistent Skyrme-Hartree-Fock and Relativistic Mean-Field theories. Due to the presence of low-lying proton continuum resulting in a free particle gas, special attention is paid to the treatment of single-particle level density. To cure the pathological behavior of shell correction around the particle threshold, the method based on the Green's function approach has been adopted. It is demonstrated that for the vast majority of Skyrme interactions commonly employed in nuclear structure calculations, the strongest shell stabilization appears for Z=124, and 126, and for N=184. On the other hand, in the relativistic approaches the strongest spherical shell effect appears systematically for Z=120 and N=172. This difference has probably its roots in the spin-orbit potential. We have also shown that, in contrast to shell corrections which are fairly independent on the force, macroscopic energies extracted from self-consistent calculations strongly depend on the actual force parametrisation used. That is, the A and Z dependence of mass surface when extrapolating to unknown superheavy nuclei is prone to significant theoretical uncertainties., 14 pages REVTeX, 8 eps figures, submitted to Phys. Rev. C