Keywords: user

Next: 27. Electron Transfer Calculations Up: user Previous: 25. Vibrational frequencies Contents
Subsections

- 26.1 `GAUSSIAN` -- Gaussian Cube format
- 26.2 `TITLE` -- Title directive
- 26.3 `LIMITXYZ` -- Plot limits
- 26.4 `SPIN` -- Density to be plotted
- 26.5 `OUTPUT` -- Filename
- 26.6 `VECTORS` -- MO vector file name
- 26.7 `WHERE` -- Density evaluation
- 26.8 `ORBITAL` -- Orbital sub-space
- 26.9 Examples
  - Charge Density
  - Molecular Orbital

# 26. DPLOT

      DPLOT
        ...
      END

This directive is used to obtain the plots of various types of electron densities (or orbitals) of the molecule. The electron density is calculated on a specified set of grid points using the molecular orbitals from SCF or DFT calculation. The output file is either in MSI Insight II contour format (default) or in the Gaussian Cube format. DPLOT is not executed until the ```task dplot`'' directive is given. Different sub-directives are described below.

# 26.1 `GAUSSIAN` -- Gaussian Cube format

      GAUSSIAN

A outputfile is generate in Gaussian Cube format. You can visualize this file using gOpenMol (after converting the Gaussian Cube file with gcube2plt), Molden or Molekel.

# 26.2 `TITLE` -- Title directive

      TITLE <string Title default Unknown Title>

This sub-directive specifies a title line for the generated input to the Insight program or for the Gaussian cube file. Only one line is allowed.

# 26.3 `LIMITXYZ` -- Plot limits

      LIMITXYZ [units <string Units default angstroms>]
      <real X_From> <real X_To> <integer No_Of_Spacings_X>
      <real Y_From> <real Y_To> <integer No_Of_Spacings_Y>
      <real Z_From> <real Z_To> <integer No_Of_Spacings_Z>

This sub-directive specifies the limits of the cell to be plotted. The grid is generated using `No_Of_Spacings` + `1` points along each direction. The known names for `Units` are `angstroms`, `au` and `bohr`.

# 26.4 `SPIN` -- Density to be plotted

      SPIN <string Spin default total>

This sub-directive specifies, what kind of density is to be computed. The known names for `Spin` are `total`, `alpha`, `beta` and `spindens`, the last being computed as the difference between and electron densities.

# 26.5 `OUTPUT` -- Filename

      OUTPUT <string File_Name default dplot>

This sub-directive specifies the name of the generated input to the Insight program or the generated Gaussian cube file. The name `OUTPUT` is reserved for the standard NWChem output.

# 26.6 `VECTORS` -- MO vector file name

      VECTORS <string File_Name default movecs> [<string File_Name2>]

This sub-directive specifies the name of the molecular orbital file. If the second file is optionally given the density is computed as the difference between the corresponding electron densities. The vector files have to match.

# 26.7 `WHERE` -- Density evaluation

      WHERE <string Where default grid>

This sub-directive specifies where the density is to be computed. The known names for `Where` are `grid` (the calculation of the density is performed on the set of a grid points specified by the sub-directive `LimitXYZ` and the file specified by the sub-directive `Output` is generated), `nuclei` (the density is computed at the position of the nuclei and written to the NWChem output) and `g`+`n` (both).

# 26.8 `ORBITAL` -- Orbital sub-space

      ORBITALS [<string Option default density>]
      <integer No_Of_Orbitals>
      <integer Orb_No_1 Orb_No_2 ...>

This sub-directive specifies the subset of the orbital space for the calculation of the electron density. The density is computed using the occupation numbers from the orbital file modified according to the `Spin` directive. If the contours of the orbitals are to be plotted `Option` should be set to `view`. Note, that in this case `No_Of_Orbitals` should be set to `1` and sub-directive `Where` is automatically set to `grid`. Also specification of two orbital files conflicts with the `view` option. orbitals are always plotted unless `Spin` is set to `beta`.

# 26.9 Examples

## Charge Density

Example of charge density plot (with Gaussian Cube output):

    start n2
    geometry
      n  0 0   0.53879155
      n  0 0  -0.53879155
    end
    basis;  n library cc-pvdz;end
    scf
    vectors  output n2.movecs
    end
    dplot
      TITLE HOMO
      vectors n2.movecs
       LimitXYZ
     -3.0 3.0 10
    -3.0 3.0 10
    -3.0  3.0  10
      spin total
      gaussian
      output lumo.cube
    end
    task scf
    task dplot

## Molecular Orbital

Example of orbital plot (with Insight II contour output):

    start n2
    geometry
      n  0 0   0.53879155
      n  0 0  -0.53879155
    end
    basis;  n library cc-pvdz;end
    scf
    vectors  output n2.movecs
    end
    dplot
      TITLE HOMO
      vectors n2.movecs
       LimitXYZ
     -3.0 3.0 10
    -3.0 3.0 10
    -3.0  3.0  10
      spin total
      orbitals view; 1; 7
      output homo.grd
    end
    task scf
    task dplot

Next: 27. Electron Transfer Calculations Up: user Previous: 25. Vibrational frequencies Contents