Automatic mode

The following input will run a geometry optimization on water, using a (almost) minimal input:

ATOMS
 O  0  0  0
 H  1  1  0
 H -1  1  0
End

Basis
End

Geometry
End

This is the input for the ADF program. You need to store it in a file, and pass it as standard input to ADF.

For example, assume you have stored the above input in a file in. Also assume that the $ADFBIN directory is in your $PATH. Then you run ADF using the following command:

adf <in >out

ADF will run, and the resulting output will be stored in the file out. If you examine the contents of this file, you will find that ADF has actually run three times: two create runs, and one geometry optimization. The fragment files produced by the create runs are saved in t21.H and t21.O, for hydrogen and oxygen respectively.

The ATOMS block key specifies the starting geometry.

The GEOMETRY key instructs ADF to perform a geometry optimization.

The BASIS block key instructs ADF to run the appropiate create runs automatically, using default values for the basis sets to use. For the xc potentials invoked with the MODEL subkey (cf. XC input block) the xc potential in the Create run will be a GGA potential rather than such a model potential, as these potentials cannot currently be applied in Create runs.

The Automatic mode will be used when the Basis key is present in the input:

BASIS
 Type bastyp
 Core coretyp
 Path apath
 Atom atompath
 ...
End

All subkeys are optional. For most calculations you need only to set the Type and Core subkeys.

Type bastyp

bastyp is the type of basis set to use, and must correspond with the name of the directory as used within $ADFRESOURCES, or within $ADFRESOURCES/ZORA for ZORA calculations.
Thus valid types are for example: SZ, DZ, DZP, TZP, TZ2P, ...
Default: DZ.

Core coretyp

coretyp is the type of frozen core to use. Allowed values: None, Small, Medium, Large.
If no basis set with core is available, an all electron basis set will be used.
If there is only one basis set with core, Small, Medium and Large are identical.
If there are two basis sets with core, Medium and Large are identical.
Default: Large.

Path apath

apath is an alternative directory with basis sets to use. ADF looks for appropriate basis sets only within this directory.
Default: $ADFRESOURCES

Atom atompath

In this subkey 'Atom' should be replaced by the name of the atomic fragment for which you want to specify the basis, for example 'O'.

Use this key to specifically select a basis set for this atom:

- an absolute path to a basis file (for example $ADFRESOURCES/DZ/O.1s)
- a relative path to a basis file (for example DZ/O.1s)
- a filename within the Type directory (for example O.1s)

An absolute path will always be used as specified.
A relative path is relative to the value of the PATH (or PATH/ZORA) subkey.
A filename is always relative to PATH/Type or PATH/ZORA/TYPE directory.

The relative path or filename will automatically switch to a ZORA basis set in case of ZORA calculations.
You can have one Atom subkey for each basic atom type in your input.

Since you pick explicitly the file to use, you are responsible for choosing a reasonable basis set.

Do not include the Fragments or Corepotentials keys when using the Basis key!

When the Basis key is present, ADF will first create fragment files for all the basic atom fragments found in the ATOMS key block. Normally this means that for each atom type in your molecule a fragment file will be created.

You may have different fragments with the same atom: add a dot and a name (without spaces) after the name of the element, as described in the ATOMS key. For example: H.1 and H.2. In this example two fragment files will be created: one for the H.1 fragment and one for the H.2 fragment. Using the ATOM subkey you may assign different basis sets to these fragments. Another consequence is that the H.1 and H.2 atoms will never be symmertry equivalent to each other.

The basis set to use follows from the subkeys (or the default values), the XC potential follows from the XC block if it is present in the input.

In case of a relativistic calculation, the DIRAC program will also be run automatically, and the create runs will include the correct relativistic key and corresponding basis sets. For ZORA calculations, ADF first tries to locate a special ZORA basis set. If this does not succeed it will use a normal basis set if the required basis set does not use a frozen core.

The resulting fragment files will be named t21.atom, with 'atom' replaced by the names of the basic atoms present. In case of a relativitic calculation, the corepotentials will be stored on t12.rel.