Section &ATOMS ...&END

In this section the positions of the atoms and the pseudopotentials are specified. The input for a new atom type is started with a "*" in the first column. This line further containes the file name where to find the pseudopotential information starting in column 2 and several labels. The first label {GAUSS-HERMIT,KLEINMAN-BYLANDER} specifies the method to be used for the calculation of the nonlocal parts of the pseudopotential. It can be omitted for Vanderbilt pseudopotentials and Stefan Goedecker's pseudopotentials. It is further possible to specify nonlinear core correction [NLCC] and the width of the ionic charge distribution [RAGGIO]. Default is no NLCC and the default value for RAGGIO is 1.2 . For Vanderbilt pseudopotentials three futher options can be specified. BINARY indicates the binary version of the output file from the atomic code. NEWF is used in conection with binary and indicates that the pseudopotential file was generated with the new version of the atomic code. TPSEU asks for an external pseudization of the localized charge. This needs some care and additional input files. The next line containes information on the nonlocality of the pseudopotential. This line is followed by a line giving the number of atoms of the current type. On the following lines the coordiantes for this atoms have to be given.

*ECPFILENAME options
{ LMAX LOC SKIP , LMAX=l [LOC=l,SKIP=l]}
NATOMS
X Y Z

X Y Z

The information on the nonlocal part of the pseudopotential can be given in two different styles. You can specify the maximum l - quantum number with "LMAX=l" where l is S, P or D. If this is the only input, the program assumes that LMAX is the local potential. You can use another local function by specifing "LOC=l". In addition it is possible to assign the local potential to a further potential with "SKIP=l". Alternatively you can specify these three angular quantum numbers by their numerical values (S=0, P=1, D=2) in the order "LMAX LOC SKIP". If values outside the range 0 - LMAX for LOC and SKIP are provided the program uses the default. Examples: The following lines are equivalent
LMAX=P
LMAX=P LOC=P
1 1 2
1 2 2

For Vanderbilt and Goedecker pseudopotentials this line has to be in a valid format, but the actual values are not used.

Further options (to be specified outside the definition range of the atomic species):

ISOTOPE

Changes the default masses of the atoms. On the NSP (number of atom types) lines following this keyword the masses of the species (in order of their definition) are specified.

MOVIE TYPE

Assign special movie atom types to the species. The types are read from the next line. Values from 0 to 5 are recognized by the MOVIE program.

GENERATE COORDINATES

The number of generator atoms for each species are read from the next line. These atoms are used together with the point group information to generate all other atomic positions. The input still has to have entries for all atoms but their coordinates are overwritten. Also the total number of atoms per species has to be correct.

CHANGE BONDS

With this keyword the buildup of the empirical Hessian can be affected. You can either add or delete bonds. The number of changed bonds is read from the next line. This line is followed by the description of the bonds. The format is
{ ATOM1 ATOM2 FLAG }.
ATOM1 and ATOM2 are the numbers of the atoms involved in the bond. A FLAG of -1 causes a bond to be deleted and a FLAG of 1 a bond to be added.
Example:
CHANGE BONDS
2
1 2 +1
6 8 -1

DUMMY ATOMS

The definition of dummy atoms follows this keyword. Two different kinds of dummy atoms are implemented. Type 1 is fixed in space and type 2 lies at the arithmetic mean of the coordinates of real atoms. The first line containes the total number of dummy atoms. The following lines start with the type label TYPE1, TYPE2. For type 1 dummy atoms the label is followed by the cartesian coordinates. For type 2 dummy atoms the first number specifies the total number of atoms involved in the definition of the dummy atom. Then the number of these atoms has to be specified on the same line. Example:
DUMMY ATOMS
2
TYPE1 0.0 0.0 0.0
TYPE2 2 1 4

CONSTRAINTS ... END CONSTRAINTS

Within this option you can specify several suboptions.

FIX ATOMS

This keyword is followed by the number of atoms to be fixed on the next line and a list of these atoms (specified by the number of their position).

FIX COORDINATES

This keyword is followed by the number of atoms with fixed coordinates and a list of these atoms together with flags indicating which coordinates are fixed. A zero indicates a fixed coordinate. Example:
FIX COORDINATES
2
1 0 0 1
4 1 0 1

FIX COM

Fix the center of mass

FIX STRUCTURE

nfix

DIST

n1 n2 R

STRETCH

n1 n2 R

BEND

n1 n2 n3

TORSION

n1 n2 n3 n4

RIGID

nr n1 n2 ... nx

A function value of -999. refers to the current value.

PENALTY

The weight factors for the penalty function for stretchs, bends, and torsions are read from the next line.