NAME

       chemps2 - spin-adapted DMRG for ab initio quantum chemistry

SYNOPSIS

       chemps2 [OPTION] ...

DESCRIPTION

       chemps2  is a scientific code to perform spin-adapted density matrix renormalization group
       (DMRG) calculations for ab initio quantum chemistry fcidump files. This method allows  one
       to   obtain   numerical  accuracy  in  active  spaces  beyond  the  capabilities  of  full
       configuration interaction (FCI) and can return the  active  space  2-RDM.  The  method  is
       therefore  ideal  to  replace  the  FCI  solver in the complete active space configuration
       interaction (CASCI) and complete active space self consistent field (CASSCF) methods.  The
       link to the user manual can be found in the section SEE ALSO.

OPTIONS

   SYMMETRY
       Conventions for the symmetry group and irrep numbers (same as psi4):

                        |  0    1    2    3    4    5    6    7
               ---------|-----------------------------------------
               0 : c1   |  A
               1 : ci   |  Ag   Au
               2 : c2   |  A    B
               3 : cs   |  Ap   App
               4 : d2   |  A    B1   B2   B3
               5 : c2v  |  A1   A2   B1   B2
               6 : c2h  |  Ag   Bg   Au   Bu
               7 : d2h  |  Ag   B1g  B2g  B3g  Au   B1u  B2u  B3u

   ARGUMENTS
       -f, --fcidump=filename
              Set  the  fcidump  filename.  Note  that  orbital irreps in this file follow molpro
              convention!

       -g, --group=int
              Set the psi4 symmetry group number [0-7] which corresponds to the fcidump file.

       -m, --multiplicity=int
              Overwrite the spin multiplicity [2S+1] of the fcidump file.

       -n, --nelectrons=int
              Overwrite the number of electrons of the fcidump file.

       -i, --irrep=int
              Overwrite  the  target  wavefunction  irrep  [0-7]  of  the  fcidump   file   (psi4
              convention).

       -D, --sweep_d=int,int,int
              Set the bond dimensions for the successive sweep instructions (positive integers).

       -E, --sweep_econv=flt,flt,flt
              Set the energy convergence to stop sweep instructions (positive floats).

       -M, --sweep_maxit=int,int,int
              Set the maximum number of sweeps for the sweep instructions (positive integers).

       -N, --sweep_noise=flt,flt,flt
              Set the noise prefactors for the successive sweep instructions (floats).

       -e, --excitation=int
              Set  which  excitation  should  be  calculated  (positive integer). If not set, the
              ground state is calculated.

       -o, --twodmfile=filename
              Set the filename to dump the 2-RDM. If not set, the 2-RDM is not dumped.

       -c, --checkpoint
              Read and create MPS checkpoints.

       -p, --print_corr
              Print correlation functions.

       -t, --tmpfolder=path
              Overwrite the tmp folder for the renormalized operators (default /tmp).

       -r, --reorder=int,int,int
              Specify an orbital reordering w.r.t. the fcidump file (counting starts at 0).

       -h, --help
              Display this help.

   EXAMPLE
        $ cd /tmp
        $ wget 'https://github.com/SebWouters/CheMPS2/raw/master/tests/matrixelements/H2O.631G.FCIDUMP'
        $ ls -al H2O.631G.FCIDUMP
        $ chemps2 --fcidump=H2O.631G.FCIDUMP \
                  --group=5 \
                  --sweep_d=200,1000 \
                  --sweep_econv=1e-8,1e-8 \
                  --sweep_maxit=2,10 \
                  --sweep_noise=0.05,0.0 \
                  --twodmfile=2dm.out \
                  --print_corr \
                  --reorder=6,5,4,3,2,1,0,7,8,9,10,11,12

AUTHOR

       Written by Sebastian Wouters <sebastianwouters@gmail.com>

BUGS

       Reporting bugs: https://github.com/sebwouters/CheMPS2/issues

SEE ALSO

       User manual: http://sebwouters.github.io/CheMPS2/index.html

COPYRIGHT

       CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry
       Copyright (C) 2013-2015 Sebastian Wouters

       This program is free software; you can redistribute it and/or modify
       it under the terms of the GNU General Public License as published by
       the Free Software Foundation; either version 2 of the License, or
       (at your option) any later version.

       This program is distributed in the hope that it will be useful,
       but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
       GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation, Inc.,
       51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.