Recover from Crash
******************

A calculation may terminate in two ways: controlled or uncontrolled.
Controlled termination includes cases where the program itself detects
an error and decides that continuation of the calculation is
impossible or pointless. In all such cases the standard exit routine
is executed, resulting in an output section with some final
information. This also ensures that the general result file adf.rkf is
closed properly and all relevant information flushed to it.

*Uncontrolled* termination may occur, for instance when some bug
causes the program to divide by zero, violate memory access
restrictions, etc. Usually this leads to an immediate abort of the
program by the operating system and hence loss of control by the
program. In such situations the information on adf.rkf may be
incomplete because some of the data are kept in memory until the final
termination of the program is carried out. ADF supports a checkpoint
file, named TAPE13, to help you recover some of the results: not for
analysis, but for continuation from a point not too long before the
fatal condition occurred. TAPE13 can be used, just like adf.rkf, as a
normal restart file in the ADF part of the input. See the RESTART key.
For restarting tasks related to exploring the PES, such as Geometry
Optimization, Linear Transit, Transition State, IRC or IR Frequencies
calculations, the ams.rkf file produced by the AMS driver is
essential. See the AMS manual.
