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Input keywords

Andreas Koehn edited this page Dec 18, 2021 · 2 revisions

Table of Contents

Keywords for GeCCo input file

The input file can have the four sections 'general', 'orb_space', 'method', and 'calculate'.

general

memmax=<integer>

Virtual memory in words (default = 50 000 000 = 400 MB); overruled by external setting via Molpro interface

da_block=<integer>

Block length (in kBytes) for direct access files (default = 32); must be kept the same for restarts

form_test

Only evaluate the formal algebra and quit without any actual numerical computations

print=<integer>

Print level (default = 3); does not have a too large effect on the output file (but on the log file) currently.

orb_space

shell

define an orbital shell, e.g.

 shell type=frozen def=(2,0,0,0)
sub keywords:
type=<type>

where <type> is one of 'frozen', 'actorb', 'deleted', 'occ', 'closed'

frozen

Freeze lowest (doubly occupied) orbitals; define either by 'def' or 'nfreeze', else orbitals with energy < 2.5 Hartree will be selected automatically

deleted

Remove highest virtual orbitals

actorb

Modify active space by either including virtual of excluding active orbitals (occupied orbitals cannot be added)

occ

define occupied orbitals (including core, inactive, active)

closed

define doubly occupied orbitals (including core and inactive)

def=(<integer>,<integer>,...)

Define shell (orbital number per IRREP)

nfreeze=<integer>

Total number of orbitals to freeze (delete) for type=frozen or deleted

nactel=<integer>

Number of active electrons for type=actorb

method

Select a method

CC

Select single-reference coupled-cluster calculation (only implemented for closed-shell cases)

maxexc=<integer>

Maximum excitation level (default=2); choose 3 for CCSDT, 4 for CCSDTQ, etc.

minexc=<integer>

Minimum excitation level (default=1); choose 2 for omitting singles (anything else is possible but insane)

truncate=<truncation>

"truncation" has the following possible values: "CC2" (requires maxexc=2), "CC3" and "CCSDT-3" (both require maxexc=3)

MR

Definitions for multireference calculations; see also MRCC section, the allocation of keywords to either section is not always well-chosen (sorry)

maxroot=<integer>

number of roots to compute in reference space (CASCI)

ciroot=<integer>

select root for subsequent correlation calculation

maxexc=<integer>

maximum excitation level (default=2) for MRCC

minexc=<integer>

minimum excitation level (default=1) for MRCC

excrestr=(hmin,hmax,pmin,pmax,excmin,excmax)

Allows detailed restrictions of the excitation manifold by an array with six elements: (hmin,hmax,pmin,pmax,excmin,excmax). The first four entries specify the excitation classes for which a restriction is given (by minimum/maximum number of hole/particle labels), the last two entries define a restriction to the excitation rank in those classes.

MRCC

select internally contracted MRCC

maxcom_res=<integer>

commutator truncation for residual (default=2)

maxcom_en

commutator truncation for energy (default=2, recommended: 4)

set_up_T_corr=<logcal>

set up amplitudes for subsequent use in (T) calculation (default=F); set to "T" if required

MRCI

select internally contracted CI

nroots=<integer>

number of roots to calculate (default=1)

calculate

solve

conv
maxiter
maxsub

properties

excitation

ionization

routes

interfaces