Provided by: chemps2_1.8.12-1_amd64 
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-, 3-, and 4-RDM. The
method is therefore ideal to replace the FCI solver in the complete active space self
consistent field (CASSCF) and complete active space second order perturbation theory
(CASPT2) 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, --file=inputfile
Specify the input file.
-v, --version
Print the version of chemps2.
-h, --help
Display this help.
INPUT FILE
FCIDUMP = /path/to/fcidump
Note that orbital irreps in the FCIDUMP file follow molpro convention!
GROUP = int
Set the psi4 symmetry group number [0-7] which corresponds to the FCIDUMP file.
MULTIPLICITY = int
Overwrite the spin multiplicity [2S+1] of the FCIDUMP file.
NELECTRONS = int
Overwrite the number of electrons of the FCIDUMP file.
IRREP = int
Overwrite the target wavefunction irrep [0-7] of the FCIDUMP file (psi4
convention).
EXCITATION = int
Set which excitation should be calculated. If zero, the ground state is calculated
(default 0).
SWEEP_STATES = int,int,int
Set the number of reduced renormalized basis states for the successive sweep
instructions (positive integers).
SWEEP_ENERGY_CONV = flt,flt,flt
Set the energy convergence to stop the successive sweep instructions (positive
floats).
SWEEP_MAX_SWEEPS = int,int,int
Set the maximum number of sweeps for the successive sweep instructions (positive
integers).
SWEEP_NOISE_PREFAC = flt,flt,flt
Set the noise prefactors for the successive sweep instructions (floats).
SWEEP_DVDSON_RTOL = flt,flt,flt
Set the residual norm tolerance for the Davidson algorithm for the successive sweep
instructions (positive floats).
NOCC = int,int,int,int
Set the number of occupied (external core) orbitals per irrep (psi4 irrep
ordering).
NACT = int,int,int,int
Set the number of active orbitals per irrep (psi4 irrep ordering).
NVIR = int,int,int,int
Set the number of virtual (secondary) orbitals per irrep (psi4 irrep ordering).
MOLCAS_2RDM = /path/to/2rdm/output
When all orbitals are active orbitals, write out the 2-RDM in HDF5 format when
specified (default unspecified).
MOLCAS_3RDM = /path/to/3rdm/output
When all orbitals are active orbitals, write out the 3-RDM in HDF5 format when
specified (default unspecified).
MOLCAS_F4RDM = /path/to/f4rdm/output
When all orbitals are active orbitals, write out the 4-RDM contracted with the Fock
operator in HDF5 format when specified (default unspecified).
MOLCAS_FOCK = /path/to/fock/input
When all orbitals are active orbitals, read in this file containing the Fock
operator (default unspecified).
MOLCAS_FIEDLER = bool
When all orbitals are active orbitals, switch on orbital reordering based on the
Fiedler vector of the exchange matrix (TRUE or FALSE; default FALSE).
MOLCAS_ORDER = int,int,int,int
When all orbitals are active orbitals, provide a custom orbital reordering (default
unspecified). When specified, this option takes precedence over MOLCAS_FIEDLER.
MOLCAS_OCC = int,int,int,int
When all orbitals are active orbitals, set initial guess to an ROHF determinant
(default unspecified). The occupancy integers should be 0, 1 or 2 and the orbital
ordering convention is FCIDUMP.
MOLCAS_MPS = bool
When all orbitals are active orbitals, switch on the creation of MPS checkpoints
(TRUE or FALSE; default FALSE).
MOLCAS_STATE_AVG = bool
Switch on writing to disk of N-RDMs of intermediate roots (TRUE or FALSE; default
FALSE).
SCF_STATE_AVG = bool
Switch on state-averaging (TRUE or FALSE; default FALSE).
SCF_DIIS_THR = flt
Switch on DIIS when the update norm is smaller than the given threshold (default
0.0).
SCF_GRAD_THR = flt
Gradient norm threshold for convergence of the DMRG-SCF orbital rotations (default
1e-6).
SCF_MAX_ITER = int
Specify the maximum number of DMRG-SCF iterations (default 100).
SCF_ACTIVE_SPACE = char
Rotate the active space orbitals: no additional rotations (I), natural orbitals
(N), localized and ordered orbitals (L), or ordered orbitals only (F) (default I).
SCF_MOLDEN = /path/to/molden
Rotate the FCIDUMP orbitals to the DMRG-SCF occupied (external core), active, and
virtual (secondary) orbitals.
CASPT2_CALC = bool
Switch on the CASPT2 calculation (TRUE or FALSE; default FALSE).
CASPT2_ORBS = char
Perform the DMRG calculation for the 4-RDM in the SCF_ACTIVE_SPACE orbitals (A) or
in the pseudocanonical orbitals (P) (default A).
CASPT2_IPEA = flt
Ionization potential - electron affinity shift (default 0.0).
CASPT2_IMAG = flt
Imaginary level shift (default 0.0).
CASPT2_CHECKPT = bool
Create checkpoints to continue the CASPT2 4-RDM calculation over multiple runs
(TRUE or FALSE; default FALSE).
CASPT2_CUMUL = bool
Use a cumulant approximation for the CASPT2 4-RDM and overwrite CASPT2_CHECKPT to
FALSE (TRUE or FALSE; default FALSE).
PRINT_CORR = bool
Print correlation functions (TRUE or FALSE; default FALSE).
TMP_FOLDER = /path/to/tmp/folder
Overwrite the tmp folder for the renormalized operators. With MPI, separate folders
per process can (but do not have to) be used (default /tmp).
EXAMPLE
$ cd /tmp
$ wget 'https://github.com/SebWouters/CheMPS2/raw/master/tests/matrixelements/N2.CCPVDZ.FCIDUMP'
$ ls -al N2.CCPVDZ.FCIDUMP
$ wget 'https://github.com/SebWouters/CheMPS2/raw/master/tests/test14.input'
$ sed -i "s/path\/to/tmp/" test14.input
$ cat test14.input
$ chemps2 --file=test14.input
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) 2013-2021 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.