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 Purpose: Build the (Hartree) product of two MCTDH wavefunctions.
 Usage : concat [-ver -D -dvr -w -h -?] psi1 psi2

Options :
 -ver    : Version information about the program
 -D DIR  : Data are stored in directory DIR,
           rather than in the current directory.
           The directory DIR will be made, if not existing.
 -dvr    : The dvr-file for the new WF will be build.
 -w      : Existing files are overwritten.
 -h      : Print this help text.
 -?      : Print this help text.
 The arguments psi1, psi2 are the names of the restart-files to be
 to be concatenated, i.e. psi = psi1*psi2 .
 If no argument is given, the user is prompted for the missing argument.
 The first WF may have electronic states  (in single- or multi-set),
 but the second WF must not have electronic states.
 Packets are not allowed.
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