MCCCS Towhee (database_input)



    This sections covers the values that are set in the database_input file. This file is only used in conjunction with the 'Database' setting of the inputformat variable. The database_input file is a work in progress and the format is not as clean as some of the other Towhee files. This manual is accurate only for the latest version of the code (last updated for version 3.14.5).
Variable explanations for database_input
    Starting with version 3.14.5 this now uses a format we call the Sandia Database (sdb). This format was created to facilitate sharing of information between various quantum and classical codes here at Sandia National Laboratories. This format is still evolving to suit our needs and is designed to use key tokens for identifying variables. In general, the keywords are read in on one line and then any associated variable are read in on the subsequent lines.
    The first line read for each entry is the datastyle and is indicated by an @ token. At the moment, there is only one supported option for this variable.
  • '@structure'
      This setting provides the template for a structure and the energy of that structure relative to a defined elemental ground state. You must define one (and only one) ground state for each of the elements in the calculation. The formatting is a bit tricky, so I have also provided a structure-energy example
      $start structure
      • An informationtional text string that serves two purposes. First, it is outputted with the results in order to provide a useful reference when determining which crystal structures are fit well and poorly. Second, if this string ends with the letters "GS" then this is set to be the defined ground state for the element.
      • The number of comment lines in the file. Unlike the other commands, this one has the number of skip lines built right into the string (in the case above, 3). This allows the user to have other information at the top of the structure-energy part that is useful for other purposes, but is not used in the structure-energy computation. Must be a non-negative integer and is the number of lines immediately following this line that are skipped.
      $distance unit
      $cell vectors
      • The hmatrix for the unit cell. Three vectors (one per line) in a similar manner as in towhee_input. Units are Angstroms.
      $number of atoms
        The number of atoms in the unit cell.
      $atom type position
        Reads in a line for each atom (as specified by number of atoms). Each line reads in an integer counter, then a character*2 atomtype and finally the 3 values of the double precision position vector for that atom
      $Ebinding cell
      • The per atom energy (relative to the specified ground state) and the units of the energy (eV is default).
      $Etotal cell
      • The absolute energy of the entire unit cell and the units of the energy (Ry is default).
Return to the main towhee web page


Send comments to: Marcus G. Martin
Last updated: September 07, 2005