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sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,830

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Generating natural orbitals for states solved by SF-TDDFT of ORCA

Today a Multiwfn user asked me how to generate natural orbitals for ground state of spin-flip TDDFT (SF-TDDFT) calculation of ORCA, here I describe the steps. This feature is supported in Multiwfn since the version updated on 2022-Apr-21.

This is an example input file of SF-TDDFT of ORCA 5.0.3:

! BHandHLYP def2-SVP
%tddft
SF TRUE
nroots 5
tprint 1E-8
end
* XYZ 0 3
C 0 0 0.1058
H 0 0.9910 -0.3174
H 0 -.9910 -.3174
*

After calculation, it can be seen that the first state is ground state of SF-TDDFT

---------------------
SF-TDA EXCITED STATES
---------------------

the weight of the individual excitations are printed if larger than 1.0e-08

(SPIN-FLIP GROUND STATE)
STATE  1:  E=   0.032744 au      0.891 eV     7186.4 cm**-1 <S**2> =   2.013446
     1a ->   3b  :     0.005097 (c= -0.07139586)
     1a ->   5b  :     0.000410 (c=  0.02024529)
...

Assume that the resulting gbw file is CH2_m3.gbw, run the following command to convert it to CH2_m3.molden.input file, which contains reference state orbitals of the SF-TDDFT calculation:

orca_2mkl CH2_m3 -molden

Boot up Multiwfn and input
CH2_m3.molden.input
18  // Electron excitation analysis
13  // Generate natural orbitals of specific excited states
CH2_m3.out  // Output file of the SF-TDDFT calculation
1  // The first state will be processed (corresponding to the ground state solved by SF-TDDFT)

Now NO_0001.mwfn has been generated in current folder, which contains natural orbitals of SF-TDDFT ground state. If you hope to convert it to other popular formats, you can reboot Multiwfn, load it, and enter subfunction 2 of main function 100, it can then be convert to e.g. molden, wfn, wfx ... formats via corresponding options.

Note that the natural orbitals generated in above way are alpha natural orbitals and beta natural orbitals, their occupancies are between 0 and 1, if you need spatial natural orbitals (i.e. spinless, occupancy is between 0 and 2), you can do following steps. Boot up Multiwfn and input
NO_0001.mwfn
100
2  // Export file
7  // Export to .fch file
[Press ENTER button]  // Use default name

Now you have NO_0001.fch in current folder. Then boot up Multiwfn and input
NO_0001.fch
200
16  // Generate natural orbitals based on the density matrix in .fch/.fchk file
SCF
1  // Spatial natural orbitals
y
Now the generated new.mwfn file contains spatial natural orbitals of the SF-TDDFT ground state.