Specify a global Debye-Waller factor to be used or added to
Debye-Waller calculations (see the DEBYE card) for all paths. This
value will be summed with the correlated Debye model value (if the
DEBYE card is present) and any value added to `list.dat'. Units are
Å. This card can be used, for example to add Debye-Waller
factors from structural disorder.
SIG2 0.001 add 0.001 globally to all DW factors