Species Characteristics

The mass of a species, the pseudopotential which represents the ion and the size of the LCAO basis set used for population anslsyis may be specified in the cell definition file.

%BLOCK SPECIES_MASS
[units]

$$\begin{array}{cc} CCC_1 \vert I_1 & R_1 \\ CCC_2 \vert I_2 & R_2 \\ \vdots \end{array}$$

%ENDBLOCK SPECIES_MASS

[units] specifies the units in which the masses are defined. If not present, the default is atomic mass units.

The first entry on a line is the symbol or atomic number of the species. This must correspond with the species symbol or atomic number of the species in the POSITIONS_FRAC or POSITIONS_ABS block. The second entry on each line is the mass of that species. Not all species need appear in the SPECIES_MASS block, any not present will assume the default mass for that species. If the initial alphabetical symbol specified for a species is not a standard element symbol in the periodic table, the mass of the species must be specified.

%BLOCK SPECIES_POT

$$\begin{array}{cc} CCC_1 \vert I_1 & <filename> \\ CCC_2 \vert I_2 & <filename> \\ \vdots \end{array}$$

%ENDBLOCK SPECIES_POT

The first entry on a line is the symbol or atomic number of the species. This must correspond with the species symbol or atomic number of the species in the POSITIONS_FRAC or POSITIONS_ABS block. The second entry on each line is the filename of the file containing the definition of the pseudopotential representing the ionic species. The file to which this refers may be a definition of the parameters of the pseudopotential which is to be generated at runtime, or an old-style pseudopotential definition containing the data for the pseudopotential.

Not all species need appear in the SPECIES_POT block. If a pseudopotential is not specified, the default pseudopotential parameters will be used to generate a pseudopotential for the element specified. If the initial alphabetical characters of a species label is not a standard element symbol in the periodic table, the potential for the species must be specified.

The charge on the ion for each species will be derived from the pseudopotential corresponding to that ion.

%BLOCK SPECIES_LCAO_STATES

$$\begin{array}{cc} CCC_1 \vert I_1 & I_{B1} \\ CCC_2 \vert I_2 & I_{B2} \\ \vdots \end{array}$$

%ENDBLOCK SPECIES_LCAO_STATES

The first entry on a line is the symbol or atomic number of the species. This must correspond with the species symbol or atomic number of the species in the POSITIONS_FRAC or POSITIONS_ABS block. The second number is the number of angular momentum channels to use in the LCAO basis set for the species when performing population analysis. For example, to use the 2s and 2p states for C (The 1s state is a core state) this should be 2. By default, the number of states will be the appropriate number to complete the valence shell to the next noble gas. If shallow core states are excluded from a pseudopotential, the value of SPECIES_LCAO_STATES for that specied should be included in the cell file to ensure a meaningful basis set is used.