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