Table of contents
Details
The QM section handles the reference and ChronusQ job type specification. The QM section is a required section for all ChronusQ jobs.
Keywords
| Keyword | Type | Description | Default | Required |
|---|---|---|---|---|
REFERENCE |
String | Type of reference wavefunction | N/A | Yes |
JOB |
String | Type of calculation | N/A | Yes |
X2CTYPE |
String | Type of X2C transformation | FULL |
No |
The REFERENCE Keyword
The QM.REFERENCE keyword allows for specification of the reference wave function for SCF and post-SCF ChronusQ calculations. ChronusQ currently supports Hartree-Fock and Kohn-Sham reference choices. The REFERENCE keyword may be constructed systematically as
REFERENCE = [ REAL/COMPLEX ] <R/RO/U/G/2C><HF/FUNCTIONAL>The REAL/COMPLEX specification is optional, and a canonical choice will be chosen for the user should it not be specified (COMPLEX for 2-Component / GIAO references, REAL otherwise). The second two keyword fields in the above template are required, and may be combined freely.
R/RO/U/G/X2C specifies the desired spin symmetry of the reference wave function: Restricted (S2 eigenfunction, even number of particles), Restricted Open (S2 eigenfunction, any number of particles), Unrestricted (Sz eigenfunction), Generalized (2-Component, no spin symmetry), X2C ("Exact" 2-Component Relativistic, with one-body spin-orbit coupling, no spin symmetry), respectively.
HF will generate a Hartree-Fock wave function, and FUNCTIONAL is a place holder to specify a Kohn-Sham wave function with the FUNCTIONAL DFT functional. (See below) RO is currently only compatible with HF, not Kohn-Sham.
DFT Functionals
ChronusQ supports the following DFT functionals (10/9/2020):
| Name | Type | Description |
|---|---|---|
SLATER |
Pure LDA Exchange | Slater exchange |
LSDA/LDA
|
Pure LDA Exchange/Correlation | Slater exchange + VWN3 correlation |
SVWN5 |
Pure LDA Exchange/Correlation | Slater exchange + VWN5 correlation |
B88 |
Pure GGA Exchange | B88 exchange |
BLYP |
Pure GGA Exchange/Correlation | B88 exchange + LYP correlation |
PBEXPBEC |
Pure GGA Exchange/Correlation | PBE exchange + PBE correlation |
B3LYP |
Hybrid GGA Exchange/Correlation | B3LYP functional |
B3PW91 |
Hybrid GGA Exchange/Correlation | B3PW91 functional |
PBE0 |
Hybrid GGA Exchange/Correlation | PBE0 functional |
BHANDHLYP |
Hybrid GGA Exchange/Correlation | BHandHLYP functional |
BHANDH |
Hybrid GGA Exchange/Correlation | BHandH functional |
Addition of more functionals is possible - if a specific functional is required for your research, please open an issue!
The JOB Keyword
The JOB keyword controls the type of calculation done by ChronusQ. The currently supported job types are:
| Value | Description |
|---|---|
SCF |
Self-consistent orbital optimization |
RESP |
Response theory |
RT |
Electron dynamics |
For more information, see the respective input sections of each.
The X2CTYPE Keyword
When the reference is specified as X2C, different methodologies can be used to define the transformation between the four- and two-component Hamiltonians. The X2CTYPE keyword controls the type of transform used.
| Value | Description |
|---|---|
FULL |
The standard X2C transformation algorithm without local approximation |
ALH |
Atomic local approximation to the Hamiltonian |
ALU |
Atomic local approximation to the transformation matrix |
DLH |
Diagonal local approximation to the Hamiltonian |
DLU |
Diagonal local approximation to the transformation matrix |
SO |
Include spin-orbit relativistic effect in X2C |
SCALAR |
Only compute scalar relativistic effect in X2C |
Examples
Restricted Hartree-Fock Energy
[QM]
Reference = RHF
Job = SCFUnrestricted Kohn-Sham (B3LYP) Response
[QM]
Reference = UB3LYP
Job = RespComplex Generalized Kohn-Sham (LSDA) Energy
[QM]
Reference = Complex GLSDA
Job = SCFRelativistic Kohn-Sham (BHandH) Electron Dynamics
[QM]
Reference = X2CBHandH
Job = RT