

## Table of contents






[[_TOC_]]






## 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 postSCF ChronusQ calculations. ChronusQ currently supports HartreeFock and KohnSham 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 2Component / 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 (S<sup>2</sup> eigenfunction, even number of particles), Restricted Open (S<sup>2</sup> eigenfunction, any number of particles), Unrestricted (S<sub>z</sub> eigenfunction), Generalized (2Component, no spin symmetry), X2C ("Exact" 2Component Relativistic, with onebody spinorbit coupling, no spin symmetry), respectively.






`HF` will generate a HartreeFock wave function, and `FUNCTIONAL` is a place holder to specify a KohnSham wave function with the `FUNCTIONAL` DFT functional. (See below) **`RO` is currently only compatible with `HF`, not KohnSham.**






#### 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!](https://urania.chem.washington.edu/chronusq/chronusq_public//issues)






### The `JOB` Keyword






The `JOB` keyword controls the type of calculation done by ChronusQ. The currently supported job types are:






 Value  Description 



    



 `SCF`  Selfconsistent 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 twocomponent 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 spinorbit relativistic effect in X2C 



 `SCALAR`  Only compute scalar relativistic effect in X2C 






## Examples






### Restricted HartreeFock Energy






```



[QM]



Reference = RHF



Job = SCF



```






### Unrestricted KohnSham (B3LYP) Response






```



[QM]



Reference = UB3LYP



Job = Resp



```






### Complex Generalized KohnSham (LSDA) Energy



```



[QM]



Reference = Complex GLSDA



Job = SCF



```






### Relativistic KohnSham (BHandH) Electron Dynamics



```



[QM]



Reference = X2CBHandH



Job = RT



``` 


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