Prev Next

LS220wl (with low densities)


This table contains the EoS by Lattimer and Swesty [LSNP_1991] with compression modulus K = 220 MeV. The nuclear interaction is an effective non-relativistic Skyrme type model without momentum dependence. Within the inhomogeneous phase at low density, nuclei are supposed to arrange themselves in a body centered cubic lattice which maximizes the separation of ions. According to the Wigner-Seitz approximation, each ion is at the center of a neutral-charged cell, surrounded by a gas of free nucleons, α-particles and electrons. Interactions between the outside gas and the nuclei are taken into account through an excluded volume. Nucleons are treated as non-relativistic particles; α-particles as hard spheres of volume v_α = 24 fm^{-3} forming an ideal Boltzmann gas. As the density increases, nuclei undergo geometrical shape deformations, until they dissolve in favor of homogeneous nuclear matter above approximately saturation density. The formation of non-spherical nuclei is described by modifying the Coulomb and surface energies of nuclei, as discussed in Section 2.8 of Ref. [LSNP_1991]. The transition to bulk nuclear matter is treated by a Maxwell construction. The configuration of matter and the balance between the different phases is given by the thermodynamically most favorable state, i.e. the one which minimizes the Helmholtz free energy of the system. This procedure, minimizing the free energy, guarantees that the LS EOS is thermodynamically consistent. Further details can be found in Ref. [LSNP_1991]. The web page contains additional information as well as the original code for downloading. The low density extension, below the validity range of the original Lattimer and Swesty EoS is based on a nuclear statistical equilibrium model, see Ref. [OFNP_2012].

Nparam = 3
Particles = npae NR
T min = 1.05e-01
T max = 1.82e+02
T pts = 162
nb min = 1.00e-12
nb max = 1.19e+01
nb pts = 255
Y min = 3.00e-02
Y max = 5.00e-01
Y pts = 51


References to the original work:
[LSNP_1991]   J. M. Lattimer and F. D. Swesty, Nucl. Phys. A 535, 331 (1991)
Further references:
[OFNP_2012]   M. Oertel, A. F. Fantina and J. Novak, Phys. Rev. C 85, 055806 (2012)

Data sheet

Data (contains all following files and data sheet)

The EoS "LS220wl (with low densities)" has not eos.init file associated so computation is not possible.

Please contact develop.compose (at)


Calculation are reserved to logged members.

Please log in