# The restart key¶

The name of the restart file must be provided with the key RESTART (see below). A list of data items is read from the file (if present on the file and only as far as significant for the new run) and used unless their usage is explicitly suppressed by the user.

Simple usage:

RESTART
File restartfile
End

restartfile
The name of a file with restart data. The path (absolute or relative) to the file must be included if the file is not local to the directory where the calculation executes. In most cases it will be a TAPE21 file from an ADF calculation, but this is not necessary. It may be any file - constructed by the user for instance - provided it has the right structure. It must be a kf file and the data to be used must be stored in sections and under variable names as defined below, which is exactly how such data are generated by a normal ADF run on TAPE21 or on the checkpoint file TAPE13. Note: the filename must not be one of the standard filenames used internally by the program, such as TAPE21, TAPE13 etc. Generally: don’t use a name like TAPEnn where nn is a two-digit number.

One can also specify a list of restart options:

RESTART
File restartfile
optionlist
optionlist
...
end


This is the list of possible options:

noSCF
Do not use any fit coefficients from the restart file as a first approximation to the (fitted) SCF density for the new calculation. Instead, the sum-of-fragments density will be used, as in a non-restart run. Note, typically noSCF should be used in combination with noORB.
noORB
Do not use orbitals from the restart file.
nogeo
Do not use the geometry - Cartesian, Z-matrix, etc. coordinates - from the restart file.
nohes
Do not use any Hessian from the restart file.
SPINFLIP atomnumbers
See the separate section about the spin-flip method for converging broken-symmetry systems.

Note: in the continuation of a Linear Transit, IRC or Frequencies run, geometric data are read from the restart file and will be used: the option nogeo is ignored. In a continued Frequencies run the input coordinates (key ATOMS) must be correct (i.e. the equilibrium geometry). In a continued LT or IRC run, the input coordinate values from atoms are ignored (but they must be supplied to give the program a preliminary count of atoms and fragments involved).