compass

Compass is used to do some preprocessing of the user's input. The main task of compass is to read molecule geometry and basis set and store them as internal data structure. The point group symmetry of molecule could be determined automatically and symmetry information will be generated.

General keywords

Basis

The following line is a string to specify the basis set name used in calculation. This string is used to locate the file in which basis set are stored. In general, there is a file with the name of capital "string" in the directory basis_library of BDF main directory. In addition to the directory basis_library, the work directory will also be searched to locate the basis set. Thus, users can write the basis set into a file with the name of "NAME" in work directory and specify in input file.

Both all-electron basis set and ECP basis set are supported. See below about ECP basis sets available in the BDF basis library.

If multiple basis sets are specified, a suffix -multi is needed after Basis. Basis-block is a synonym for Basis-multi. Then the first basis set (or basis set file) in the next line is the default one, and in the subsequent lines different basis sets (or basis set files) may be assigned to different elements in the format

• Ele_1, Ele_2, ..., Ele_n = basis_set_name

The Basis input block may be ended by End Basis, which is usually optional but required for Basis-block or Basis-multi.

Examples:

$Compass
Basis
 cc-pvdz
Geometry
  H  0.000   0.000    0.707
  H  0.000   0.000   -0.707
End Geometry
$End

$Compass
# ECP basis set is used.
Basis
 SBKJC-VDZ
Geometry
  Br 0.000   0.000    0.000
  I  0.000   0.000    2.500
End Geometry
$End

$Compass
# multiple basis sets with ECP for Xe. "End Basis" is needed.
Basis-multi
 3-21g
 C,N = 6-31g
 Xe = cc-pvdz-pp
End Basis
Geometry
H    0.0  0.0 -1.1
C    0.0  0.0  0.0
N    0.0  0.0  1.0
Xe   3.0  0.0  0.0
End geometry
$End

If one wants to assign different basis sets to the same element, one can do so by labeling atoms using numbers:

$compass
title
 CH4+OH transition state
basis-multi
# This assigns 3-21G to C, O and the hydrogen labeled by H1, and STO-3G for other H's
 STO-3G
 C,O,H1 = 3-21G
end basis
geometry
 C                 -1.30476780   -0.28217649    0.01651161
 H1                 0.06922223   -0.06461901   -0.06668006
 H                 -1.52745706    0.09005560    1.00578897
 H                 -1.67541520    0.37402566   -0.75763714
 H                 -1.66524887   -1.32013775   -0.12243054
 O                  1.24625883    0.22654592   -0.07441161
 H                  1.43958218    1.19260549    0.09238462
end geometry
skeleton
$end

RI-J/RI-K/RI-C

Define auxiliary basis sets used in RI calculation. RI-J: Coulomb fitting. RI-K: exchange fitting, RI-C: correlation fitting.

Examples:

$Compass
Basis
 DEF2-SVP
RI-J
 DEF2-SVP
Geometry
  H  0.000   0.000    0.707
  H  0.000   0.000   -0.707
End Geometry
$End

Geometry

The cartesian coordinates of a molecule are written as following lines with the format of

• Atom x y z

The string End of geometry is used to specify the end of the geometry input. The "xyz" formatted file can also be used as molecule geometry input. Users can write molecule geometry into a file named "test.xyz" (if your input file named test.inp, the input geometry should be stored in test.xyz using standard xyz format) and put it in work directory. The compass will read molecule geometry from this file.

Examples:

$Compass
Basis
  cc-pvdz
Geometry
  H  0.000   0.000    0.707
  H  0.000   0.000   -0.707
End Geometry
$End

Geometry is read from a file filename.xyz in the standard xyz format

$Compass
Basis
  cc-pvdz
Geometry
  file=filename.xyz
End of Geometry
$End

For a xyz file with the default name $bdftask.xyz, one may also simply specify xyz instead of file=filename.xyz.

Geometry is read as an internal coordinate.

$Compass
Basis
  cc-pVDZ
Geometry
O
H 1 0.95
H 1 0.95 2 109.0
End Geometry
$End

Restart

Use [taskname].optgeom (herein [taskname] is the name of the input file with .inp stripped off), rather than the geometry specified in the input file, as the input geometry. Useful in restarting geometry optimizations (such that the user does not need to copy the coordinates in the .optgeom file into the input file).

Group

The following line is used to set the point group of the molecule used in calculation. Usually, the point group can be determined by BDF automatically. However, the point group with degenerated representation is only supported by BDF in HF/DFT/TDDFT calculations. In general, D2h and subgroup is used by most of BDF modules. By default, BDF will use highest ablian group of a molecules point group in calculation if use do not set "Skeleton" keyword. Users can specify the subgroup of molecule point group in calculation.

For Abelian group symmetries, the numbering of irreps is

Examples:

A linear molecule CH has the Cinfv linear symmetry. We can use highest albeilian subgroup in calculation

$Compass
Basis
  sto-3g
Geometry
  C   0.0   0.0    0.0
  H   0.0   0.0    1.6
End Geometry
Group
  C(2v)
$End

Nosymm

This keyword is used to turn off the molecule symmetry in the calculation.

Norotate

Disables rotation to standard orientation. Mandatory for QM/MM.

Difference between Norotate and Nosym. The keyword "Nosymm" disables using the molecular point group symmetry. The molecular symmetry does not be checked abd the input coordinates are not rotated. C1 group is used in the calculation. The keyword "Norotate" still checks the molecular symmetry according to the input coordinates but the molecular coordinates are not rotated to standard orientation. The molecular point group is still used in the calculation.

Thresh

The threshold for detecting point group symmetry. Possible values: tight, medium, coarse. Default: tight.

Unit

This keyword is used to set the unit of input coordinate. "Bohr" is for the atomic unit. "Angstrom" is for angstrom. The angstrom is used for default.

Examples:

$Compass
Basis
  cc-pvdz
Geometry
  H  0.000   0.000    1.5
  H  0.000   0.000  -1.5
End Geometry
Unit
 Bohr
$End

Skeleton

This keyword ask the skeleton matrix method is used in the calculation. The symmetry-adapted integrals will not be generated and the symmetry-independent integrals will be used to calculate the skeleton Fock/J/K matrices in the calculation. The integral direct SCF and post-HF calculation use this method in the calculation. The none-abelian group can be used in calculation when Skeleton is asked.

Skeleton is a default keyword now but incompatible with wavefunction theory based post-HF methods; use the Saorb keyword instead in the latter case.

Example:

A CH4 molecule has the Td symmetry, we can use Td group in SCF calculation.

$Compass
Title
 CH4 Molecule test run, 3-21G
Basis
 3-21G
Geometry
 C   0.000000   0.000000   0.000000
 H   0.617765   0.617765   0.617765
 H  -0.617765  -0.617765   0.617765
 H  -0.617765   0.617765  -0.617765
 H   0.617765  -0.617765  -0.617765
End geometry
Skeleton
$End

Saorb

This keyword requests the symmetry-adapted integrals to be generated. It also requests the traditional integral indirect SCF procedure.

Extcharge

Define the type of external charge in the calculation. If the input file is named $bdftask.inp, then a file with name $bdftask.extcharge should be put into the working directory to input charges and coordinates. The value should be point and gaussian.

$COMPASS
Title
 H2 Molecule test run, 3-21G
Basis
 cc-pvdz
Geometry
 H 0.000  0.000     0.70018162
 H 0.000  0.000   -0.70018162
 X 0.000  0.000     0.80018162
 X 0.000  0.000   -0.80018162
 X 0.000  0.000     0.60018162
 X 0.000  0.000   -0.60018162
End geometry
Check
Unit
 Bohr
nosymm
ExtCharge
 Point
$END

The format of the $bdftask.extcharge file should be:

First line: an arbitrary title
Second line: number of charges and unit of coordinates (Angstrom (default) or Bohr), delimited by a space
From the third line on, each line denotes a point charge and consists of five fields: element name, amount of charge, x coordinate, y coordinate, z coordinate

Example:

External charge, Point charge
4 bohr
        C   -0.27           0.0000000000         0.0000000000        -1.4431177457
        H    0.09           1.6563586362         0.9562991045        -2.1854206090
        H    0.09          -0.0000000000        -1.9125982090        -2.1854206090
        H    0.09          -1.6563586362         0.9562991045        -2.1854206090

Restart

Use the coordinates in $BDFTASK.optgeom as the input structure, instead of that given under the "geometry" keyword in the $compass block of the current input file. Note that geometry must still be provided in the input file, which has the same number and order of atoms, but the coordinates may be arbitrary. This keyword is especially useful in restarting geometry optimizations.

MPEC+COSX

Ask for MPEC+COSX calculation if it is available.

Nfragment

The number of molecular fragments. The molecular fragments information will be read from &database ... &end domain.

GODetail

Print detail information of the symmetry-adapted orbital as linear combination coefficients, components of atomic orbitals.

PRINT

Print level. Not be used intensively at present. It is better to use this keyword to set the global print level in all BDF modules.

Values: 0 (Default), >5 (debug).

ExpBas

Export the basis functions used for the given atoms in the format of some other programs.

The available values are 0 (Default), 1 (Molpro), 2 (Molcas), 3 (Gaussian), 4 (ORCA), and 5 (CFour).

Relative

Relativistic calculation using spinor orbital. Only for debug, not well implemented yet.

Expert keywords

Uncontract

This keyword asks to use primitive GTOs instead of contracted ones.

Prim

This keyword asks to read primitive GTOs from a specific basis file. In the basis file, ncont must equal to nprim and the contraction coefficients are not provided.

Atommass

Define the atomic mass. Unit in Dalton.

2  # number of atoms
C   13.10       # label mass
H   2.00        # label mass

Kratzer

Non-adibatic diatom molecule calculation. Next line is used to specify the parameters of Kratzer potential. Three integers and two floats are needed.

$COMPASS
Title
 H2 Molecule test run, 3-21G
Basis
 cc-pvdz
Geometry
 H 0.000  0.000     0.70018162
 H 0.000  0.000   -0.70018162
 X 0.000  0.000     0.80018162
 X 0.000  0.000   -0.80018162
 X 0.000  0.000     0.60018162
 X 0.000  0.000   -0.60018162
End geometry
Check
Unit
 Bohr
nosymm
Kratzer
# maxnu maxj ngausslag re         de
 10   0   50 1.40036324  0.365148
$END

ECP basis sets

At the moment the following ECP basis sets are available in the basis library.

Used files