Core-Ionization

The Core-ionization is possible for both spin-orbital and spin-summed RHF framework. The 4-component relativistic corrections can be included using DIRAC interface.

The keywords for controlling core-ionization

%cc

incore 5/4/3/2 # Corresponding to no of virtuals index stored on disk

cc_restart 3 # CCSD energy calculated from stored converged amplitudes

NumProc _ # No of processors being used

DF

NRoots

fnothresh

fnothresh_ex

DoNataux

Nataux_thresh

Nataux_thresh_ex

DoCore False # Target the core orbitals

CoreHole 0 # Orbital from which the root counting in started

DoCVS False # Enables the core-valence separation true

CVSMIN 0 #

CVSMAX 0

DoR3OPT

DoR3CVS

DoR3CVSOPT

DoADC2

end

Core Ionization with IP-EOM-CCSD

A typical input file for core-ionization with IP-EOM-CCSD

! IP-EOM-CCSD aug-cc-pVDZ SPINORBITAL Bohr

%cc

NRoots 1

DoCore True

cc_convergence 1e-7

end

*xyz 0 1

O 0.000000000000 -0.143225816552 0.000000000000

H 1.638036840407 1.136548822547 -0.000000000000

H -1.638036840407 1.136548822547 -0.000000000000

The output is

Root: 1 IP value: 0.4359 a.u. 11.860471 eV

Dominant Transition

9 --> 0.93

It shows that the first IP value of water

Core Ionization with IP-EOM-CCSD*

The triples correction can initiated with IP-EOM-CCSD* keyword

! IP-EOM-CCSD* aug-cc-pVDZ SPINORBITAL Bohr

%cc

NRoots 1

DoCore True

cc_convergence 1e-7

end

*xyz 0 1

O 0.000000000000 -0.143225816552 0.000000000000

H 1.638036840407 1.136548822547 -0.000000000000

H -1.638036840407 1.136548822547 -0.000000000000

The Output is

--------IP-EOM-CC Triples Correction-----------

Root: 1 EOM-CCSD IP value 544.221722 eV Triples Correction -2.014933 eV Final EOM-CCSD* IP value 542.206788 eV

The triples correction leads to lowering of the IP value by 2.01 eV and much better agreement with experiment. Rest of the error is due to the smaller basis set. Simulation of core-ionization requres much larger basis

Core Ionization with FNO IP-EOM-CCSD*

A sample input file will look like

! FNO-IP-EOM-CCSD* unc-6311++g** Bohr aug-cc-pvtz-ri

%cc

incore 3

pct_occ 0.995

DoADC2 True

NRoots 2

CVSMIN 0

CVSMAX 1

CoreHole 0

DoCVS True

DoCore True

DF True

cc_convergence 1e-6

end

*xyz 0 1

C 0.00000 0.00000 0.00000

O 0.00000 0.00000 -2.19265

O 0.00000 0.00000 2.19265

*

The Output is

--------------------------------------------------

- -

---------PT2 corrected EOM-CCSD* values-----------

- -

--------------------------------------------------

root 1 Uncorrected EOMP-IP-CCSD* value 542.2887131992753 eV PT Correction -0.4347806417118026 eV Final 541.8539325575636 eV

1 --> -0.9411833842733173

root 2 Uncorrected EOMP-IP-CCSD* value 542.2906255186488 eV PT Correction -0.4347989856053473 eV Final 541.8558265330435 eV

0 --> -0.9411752675425874

Core Ionization Dual FNO IP-EOM-CCSD*

One can use two different for the threshold for the ground and ionized state.

A sample input file will look like

! BI-FNO-IP-EOM-CCSD* aug-cc-pVTZ aug-cc-pvtz-ri

%cc

incore 3

pct_occ 0.99

pct_occ_ex 0.995

DoNataux True

Natauxpct 30

NRoots 1

DoCVS True

DF True

DoCore True

DoADC2 True

end

*xyz 0 1

O 0. 0. 0.

H 0. -0.757 0.587

H 0. 0.757 0.587

*

The Output is

--------------------------------------------------

- -

---------PT2 corrected EOM-CCSD* values-----------

- -

--------------------------------------------------

root 1 Uncorrected EOMP-IP-CCSD* value 539.2777859299792 eV PT Correction 0.05280845640562867 eV Final 539.3305943863849 eV

0 --> -0.9453821023738714

The Keyword DoNataux True enables the trancation of auxilary orbital using natural auxilary orbitals. Natauxpct 30 denotes only 30% of the total auxilary orbitals are kept

Core Ionization R3CVS

A sample input file will look like

! BI-FNO-IP-EOM-CCSD* 6311++g** aug-cc-pvdz-ri

%cc

incore 4

NRoots 1

DoCVS True

CVSMAX 0

DF True

DoCore True

DoR3OPT True

DoR3CVS True

pct_occ 0.99

pct_occ_ex 0.995

DoNataux True

Natauxpct 30

DoADC2 True

end

*xyz 0 1

O 0.000000000000 0.000000000000 0.000000000000

C 0.000000000000 0.000000000000 -1.128000000000

*

The Output is

--------------------------------------------------

- -

---------PT2 corrected EOM-CCSD* values-----------

- -

--------------------------------------------------

root 1 Uncorrected EOMP-IP-CCSD* value 542.943972342854 eV PT Correction -0.2257243439486594 eV Final 542.7182479989053 eV

0 --> -0.9421501993813002

XES spectra with IP-EOM-CCSD*

A sample input file will look like

! XES-IP-EOM-CCSD* cc-pVDZ aug-cc-pvtz-ri

%cc

incore 3

NRoots 3

DoCore True # Core ionization

CoreHole 0 # Core orbital from which the ionization takes place

DoCVS True # Use core valence separation

CVSMIN 0 # The minimum orbital included to core valence separation

CVSMAX 1 # The maximum orbital used for core-valence separation

end

*xyz 0 1

O 0. 0. 0.

H 0. -0.757 0.587

H 0. 0.757 0.587

*

The Output is

----------------------

XES SPECTRA EOM-CCSD

----------------------

root 1 IP value 19.533122114873127 531.5353189899275

Dominant Transition

0 --> 4

root 2 IP value 19.44791697928015 529.2167168401714

Dominant Transition

0 --> 3

root 3 IP value 19.288394836991284 524.8758003042068

Dominant Transition

0 --> 2

----------------------

XES SPECTRA EOM-CCSD*

----------------------

root 1 IP value 19.472203723921638 529.8776077353556

Dominant Transition

0 --> 4

root 2 IP value 19.387265446732705 527.5662673364903

Dominant Transition

0 --> 3

root 3 IP value 19.23019002621276 523.2919309933017

Dominant Transition

0 --> 2

XES spectra with BI-FNO-IP-EOM-CCSD*

It uses the BI-FNO approximation for the calculation

A sample input file will look like

! XES-BI-FNO-IP-EOM-CCSD* cc-pVDZ aug-cc-pvtz-ri

%cc

incore 3

NRoots 3

pct_occ 0.99 #FNO threshold for ground state

pct_occ_ex 0.995 #FNO threshold for excited state

DoNataux True # Natural auxiliary orbital

Natauxpct 30 # Threshold for natural auxiliary orbital

DF True # Density Fitting On

DoCVS True

DoCore True

end

*xyz 0 1

O 0. 0. 0.

H 0. -0.757 0.587

H 0. 0.757 0.587

*

The Output is

----------------------

XES SPECTRA EOM-CCSD

----------------------

root 1 IP value 19.535057939599632 531.5879966523852

Dominant Transition

0 --> 4

root 2 IP value 19.448941373977863 529.2445926686856

Dominant Transition

0 --> 3

root 3 IP value 19.28916569820228 524.8967769794804

Dominant Transition

0 --> 2

----------------------

XES SPECTRA EOM-CCSD*

----------------------

root 1 IP value 19.474346928383227 529.9359286151644

Dominant Transition

0 --> 4

root 2 IP value 19.388632922121342 527.603479076766

Dominant Transition

0 --> 3

root 3 IP value 19.2314922163473 523.3273661912427

Dominant Transition

0 --> 2