Sandia National Laboratories Tramonto
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Dimension Control Parameters

These parameters defines what kind of dimensions will be set in the input file. Note that if these values are set to any negative number, it is assumed that the input is all provided in dimensionless parameters. Otherwise the values entered here will be used to reduce all other parameters provided. For more information on the details of dimensionless parameters in Tramonto calculation, see the Reduced Units web page.

  • Length_ref(real): Typically will be -1.0 to indicate that length parameters will be entered in reduced units (L/sigma). Alternatively, Length_ref may indicate characteristic size(diameter) of one of the fluid species in the problem in some real units. If Length_ref>0, then other distance variables (e.g. Size_x) must all be entered in the same real units. Tramonto will then reduce those length parameters as Length/Length_ref.
  • Density_ref(real): Typically set to -1 to indicate that reduced units will be entered in dft_input.dat. Alternatively, this parameter can be set to a real number that provides an appropriate conversion factor between the real unit densities desired for entry in the input file (e.g. Molar) and reduced densities in units rho*sigma^3. If Density_ref>0, Tramonto reduces input densities (e.g. Rho_b) using the formula density/Density_ref.
  • Temp(real): Must be either -1 (to indicate reduced units) or the temperature in K. If Temp>0 then all energy parameters (e.g. Eps_ff) must be provided as E/k(units of Kelvin) where where k is the Boltzmann constant. In this case Tramonto will compute reduced energies E/kT using the temperature provided.
  • Dielec_ref(real): Typically will be -1 (in order to set a default value of Dielec.const of 78.5). Alternatively, the dielectric constant may be entered manually here.
  • VEXT_MAX(real): This parameter is always >0 and entered in kT units. This is the maximum external field where DFT equations will be solved. if Vext>VEXT_MAX then the fluid density is set strictly to zero. Note density is proportional to the exp(-Vext/kT) so large Vext results in very small densities that can cause numerical problems in the solution of the equations. VEXT_MAX is typically between 10 and 20.