Table of Contents

• Table of Contents
• The Basis Section
  • Details
  • Keywords
    • The BASIS Keyword
    • The BASISTYPE Keyword
  • List of Built-in Basis Sets
    • Non-relativistic Bases
    • Relativistic Bases
• The DFBasis Section
  • Details
  • Keywords
  • List of Built-in Auxiliary Basis Sets
• the PBasis Section
  • Details
  • Keywords
  • List of Protonic Basis Sets
• Examples
  • Built-in Basis
  • Basis on Filesystem
  • Basis Specified in Input File

The Basis Section

Details

The BASIS section handles the basis set specification for the ChronusQ job. The BASIS section is a required section for all ChronusQ jobs and must include either the BASIS keyword or the DEFINEBASIS and BASISDEF keyword pair.

Keywords

The BASIS Keyword

The BASIS keyword may specify a supported basis set (see below) or a path to a file containing a Gaussian94 formatted basis set definition. Note that when specifying a path rather than a keyword, the path is case sensitive. Currently, multiple basis sets cannot be used for the same atom type. If this feature is important for your usage of ChronusQ, please open an issue.

The BASISTYPE Keyword

In order to model magnetic fields without an arbitrary origin dependence, basis functions that include the gauge origin dependence are necessary. These are often referred to as "London orbitals" or "Gauge Including Atomic Orbitals." (GIAO) As of 0.2.1, ChronusQ has support for GIAO bases in both the SCF and RT modules. The type of basis is controlled by the BASISTYPE keyword - either GTO for traditional Gaussian Type Orbitals (this is the default) or GIAO for GIAOs. Note that magnetic fields will be ignored if BASISTYPE is GTO.

One may set the magnetic field using the SCF.FIELD or RT.FIELD keywords. (See the SCF and RT wiki pages for more details)

List of Built-in Basis Sets

Below is the list of bases that ChronusQ currently provides. If there is a basis that you would like added to the collection, please open an issue!

Non-relativistic Bases

Relativistic Bases

The DFBasis Section

Details

The DFBASIS section handles the density fitted basis set specification for the ChronusQ job. It is not a required section. If specified, it must include either the BASIS keyword or the DEFINEBASIS and BASISDEF keyword pair.

Keywords

The keywords from the BASIS section are also available in the DFBASIS section. The DFBASIS keywords only control the auxiliary basis used in the resolution of identity (RI) approximation. The RI approximation is also available through a Cholesky decomposition of the ERI tensor even if an auxiliary basis is not specified.

List of Built-in Auxiliary Basis Sets

the PBasis Section

Details

Just like the Basis section, a separate section must be specified for using NEO basis sets for quantum nuclei. This section follows the same conventions as the electronic basis section described previously, including functionality to define a protonic basis not included within CQ. Note that the BASISTYPE keyword is not implemented currently.

Keywords

Below is a list of currently-implemented protonic basis functions.

List of Protonic Basis Sets

Examples

Built-in Basis

Example with a built-in GTO basis and density fitted basis. Both the GTO and density fitted basis are used with Cartesian basis functions.

[BASIS]
basis = 6-31G(d) 
forcecart = true

[DFBASIS]
basis = cc-pvdz-rifit
forcecart = true

Basis on Filesystem

[BASIS]
basis = /home/path/to/basis/basisset.gbs

Basis Specified in Input File

Custom basis sets require the Gaussian format.

[BASIS]
DefineBasis = On
BasisDef:
  ****
  H     0 
  S   3   1.00
       18.7311370              0.03349460       
        2.8253937              0.23472695       
        0.6401217              0.81375733       
  S   1   1.00
        0.1612778              1.0000000        
  ****
  O     0 
  S   6   1.00
     5484.6717000              0.0018311        
      825.2349500              0.0139501        
      188.0469600              0.0684451        
       52.9645000              0.2327143        
       16.8975700              0.4701930        
        5.7996353              0.3585209        
  SP   3   1.00
       15.5396160             -0.1107775              0.0708743        
        3.5999336             -0.1480263              0.3397528        
        1.0137618              1.1307670              0.7271586        
  SP   1   1.00
        0.2700058              1.0000000              1.0000000        
  D   1   1.00
        0.8000000              1.0000000        
  ****