In general, the input is made using ascii files. This enables a system to be set up with the minimum of effort. In particular, simple model system can be studied without any need to program. Options available include
Special features of the MCTDH wavepacket propagation are that:
mctdh<ver> [-opt] arguments
where ver is the version number (and optionally a "d" or a name) and arguments specifies any arguments required by the program.
To find the possible options and arguments required for a program, the argument -h can be used. For example, to find the possible options for the MCTDH program version 8 release 4 type:
As the help text says, typically an argument specifying the input file is required. Assume your input file is named test.inp and your current directory is the directory on which test.inp resides, then you may just type:
In case you have employed the options "-d" and "-n myver" in the compilation of the program (see Compiling the Program in Installation and Compilation), and your input file is not stored in your current directory but in the one specified by path, then you will have to type:
Note that the usual bash shortcuts are allowed to specify the path, e.g. the constructs ../test or ~/test are possible.
You may also run the input file through the C preprocessor
(CPP) prior to interpretation. This way, you can share basis
sets, initial states or any other settings between several input
files by using a statement of the form
This assures automatic consistency for the settings in the include file(s). To invoke CPP prior to interpretation by MCTDH, type
mctdh84 -cpp test.inp
The output of CPP is saved in a temporary file in the
directory where the input file resides. Please make sure that
this directory has write permission for MCTDH. In addition to
this, MCTDH saves the settings as it understands them in the file
input in the name directory. You can check this to see
whether MCTDH received the correct settings and CPP worked as
Note that, when the -cpp option is used, it may be possible that CPP gets confused by comments starting with a hash character '#'. To be on the safe side, use C-style comments of the form
Note that MCTDH interprets '/*' like '#', i.e. everything which follows til the end of the line is a comment and is thus ignored. The end-of-comment sign */ is only needed for CPP. Thus a comment /*..*/ must not go over several lines, on has to bracket each line individually.
For an example see inputs/allene_b.inp and inputs/allene_common1.inc
On top of include files, you may of course use any other of the multiple powerful features of CPP, such as environment variable dependencies or macros. A full documentation of CPP can be found on this Free Software Foundation webpage.
As a final example, a continuation run may be started as:
mctdh84 -c -I name -tfinal 250.0d0
The input is now taken from the file name/input rather than requiring a .inp file.
The use of options is often more convenient than changing the input file. For example, parameters are used to specify the input or the Hamiltonian. If different values are required for different calculations, one can either have different files specifying the different operators, or else different calculations can be started using the -p option, followed by a parameter name and a parameter value. E.g.:
mctdh84 -p jtot 8 -p omega 0.35,eV test.inp
NB: Parameters are always real numbers.
Finally, the command
prints information about the program version, included potential energy surfaces, and the date and time of the compilation. And the command
lists the set of the currently used maximal parameter values.
The format of the various files is governed by the program version number, and are detailed in the Output documentation.