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Charged Systems: Dielectric Constant Parameters

These parameters detail the treatment of the dielectric constant parameters when Type_coul is turned on, and Poisson’s equation is to be solved.

  • Type_dielec(int): Flag for the treatment of dielectric constants. Options are:
    • 0: uniform dielectric constant everywhere in the domain.
    • 1: set different dielectric constants for fluid regions and surface regions in the computational domain.
    • 2: set different dielectric constants for bulk fluid, restricted fluid (i.e. in a pore), and surface regions in the computational domain.
    • 3: set a constant dielectric constant in a surface, but allow variation with density in the fluid (for use with Type_coul=3 option).
  • Sigma_Angstroms_plasma(real): The particle diameter d, in angstroms, used in calculating the reduced temperature Telec = 4πkTκε0d/e2 (in MKS units). A physical value for d is needed here, since it’s possible in the code to use a dimensionless value for σref. The parameter Telec appears in the dimensionless form of Poisson’s equation (see the Reduced Units web page). It is related to the Debye length; also note that the Bjerrum length is lB = d/Telec.
  • Temp_K_plasma(real): The temperature T in Kelvin used in calculating Telec.
  • DielecConst_plasma(real): The dielectric constant κ used in calculating Telec.
  • Dielec_bulk(real): The dielectric constant of the bulk fluid. If Dielec_ref<0, enter the ratio κ/78.5. If Dielec_ref>0, enter the dielectric constant κ.
  • Dielec_pore(real): The dielectric constant for a “restricted” fluid (e.g. a fluid confined in a pore or near a surface). Again enter the ratio κpore/78.5 if Dielec_ref<0 otherwise enter κpore.
  • Dielec_X(real): The distance from the surfaces where the fluid will be considered to be restricted by a surface, and where Dielec_pore will be used.
  • Dielec_wall[Nwall_type](real vector): The dielectric constant to be used inside the surfaces in the system (where ρ=0). Note that different surface types may be assigned different dielectric constants. Again enter the ratio κsurf/78.5 if Dielec_ref<0 otherwise enter κsurf.

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