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qp2/src/bitmask
2019-01-25 11:39:31 +01:00
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bitmask_cas_routines.irp.f Initial commit 2019-01-25 11:39:31 +01:00
bitmasks_module.f90 Initial commit 2019-01-25 11:39:31 +01:00
bitmasks_routines.irp.f Initial commit 2019-01-25 11:39:31 +01:00
bitmasks.ezfio_config Initial commit 2019-01-25 11:39:31 +01:00
bitmasks.irp.f Initial commit 2019-01-25 11:39:31 +01:00
core_inact_act_virt.irp.f Initial commit 2019-01-25 11:39:31 +01:00
example.irp.f Initial commit 2019-01-25 11:39:31 +01:00
find_hole.irp.f Initial commit 2019-01-25 11:39:31 +01:00
modify_bitmasks.irp.f Initial commit 2019-01-25 11:39:31 +01:00
mpi.irp.f Initial commit 2019-01-25 11:39:31 +01:00
NEED Initial commit 2019-01-25 11:39:31 +01:00
README.rst Initial commit 2019-01-25 11:39:31 +01:00

==============
bitmask module
==============

The central part of this module is the :file:`bitmasks_module.f90` file. It contains
the constants that will be used to define on which kind of integer the bitmasks
will be defined.

In the program, to represent a determinant as a pair of bitstrings,
the determinant should be defined as

.. code-block:: fortran

  use bitmasks
  integer(bit_kind)  :: determinant(N_int,2)


:file:`bitmasks_routines.irp.f` contains helper routines to manipulate bitmask, like
transforming a bit string to a list of integers for example.


`bit_kind_shift`, `bit_kind_size` and `bit_kind` are supposed to be consistent::

   2**bit_kind_shift = bit_kind_size
   bit_kind = bit_kind_size / 8


For an example of how to use the bitmaks, see the file :file:`example.irp.f`.