[QE-users] The orbitals of a hydrogen atom

Pietro Davide Delugas pdelugas at sissa.it
Fri Oct 11 14:47:46 CEST 2024


Dear Toshiharu

If you compute the ILDOS of a system with spherical symmetry, such as the H atom, you should get a spherically symmetric distribution. For example, the 3 p orbitals will have the same energy, and when computing the ILDOS in their energy span, you will get the contributions of p_x, p_y, and p_z, thus creating an isotropic plot.
You may try to get something different, breaking the spherical symmetry, such as an atom with partially filled shells. You might find a case like that in the pw_atom directory of the QE test suite.

Otherwise, plot the charge density contribution of single orbitals with plot_num = 7. An example of this for molecules is here:
https://gitlab.com/pietrodelugas/materials-for-max-qe2021-online-school/-/tree/master/Day-1?ref_type=heads

best regards
Pietro
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Toshiharu Higuchi via users <users at lists.quantum-espresso.org>
Sent: Friday, October 11, 2024 14:10
To: "'Quantum ESPRESSO users Forum'" <users at lists.quantum-espresso.org>; "'ROBERT MIKHAIL GUZMAN ARELLANO'" <rguzmana at unmsm.edu.pe>
Subject: Re: [QE-users] The orbitals of a hydrogen atom


Dear Professor Robert,

thank you very much for your helpful comment.

According to your explanation, a pseudopotential only reproduces the valence states (occupied) and the lowest energy unoccupied states. If you open the pseudopotential used in your input file, you will see that it reproduces only the *s* and *p* states of hydrogen atoms.

However, in my calculations, the orbit is spherical even in the *p* state.

Could you please tell me the reason for this?



Best regard,

Toshiharu Higuchi



From: ROBERT MIKHAIL GUZMAN ARELLANO <rguzmana at unmsm.edu.pe>
Sent: Friday, October 11, 2024 5:11 AM
To: toshi1higu at docomo.ne.jp; Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] The orbitals of a hydrogen atom



Dear Toshiharu,

Thank you very much for sharing your input files for pw.x and pp.x.

I believe this might be the information you're looking for regarding how to plot a specific Kohn-Sham orbital: https://www.youtube.com/watch?v=FrY8Sj0zUus

On another note, pseudopotentials do not include all atomic orbitals of the atoms. A pseudopotential only reproduces the valence states (occupied) and the lowest energy unoccupied states. If you open the pseudopotential used in your input file, you will see that it reproduces only the s and p states of hydrogen atoms. If you are interested in d orbitals, you can use a pseudopotential for elements like Nickel or Cobalt.

Best regards,



El mié, 9 oct 2024 a las 20:57, Toshiharu Higuchi via users (<users at lists.quantum-espresso.org<mailto:users at lists.quantum-espresso.org>>) escribió:

Dear members of Quantum-Espresso,
I am a beginner of Quantum-Espresso. My question is about the orbital of a
hydrogen atom. I calculated the orbital of a hydrogen atom using
Quantum-Espresso. The orbitals of the hydrogen atom have already been
analytically solved.  These orbitals are (1) s-orbital is a spherically
symmetric orbital, (2) p-orbitals have two lobes with a node located at the
nucleus, and (3) d-orbitals have two types of orbitals, one kind of orbitals
consist of a cloverleaf shape, with four electron-dense lobes, and another
type of orbital has two lobes oriented in the z-axis with a donut-shaped
ring in the x-y plane.

However, the orbitals obtained with Quantum-Espresso (assuming the ILDOS
pattern as the orbital) were all spherically symmetric orbitals from the
first orbital to the tenth orbital. I was not able to obtain a pattern with
a shape like p-orbital or d-orbital.
Could someone tell me why the orbital turned out like this?

My input data is as follows.

[1] pw.x input
&CONTROL
                       title = 'QE_H_atom_Orbital_2' ,
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,
                  wf_collect = .true. ,
                      outdir = '/home/user/tmp/' ,
                  pseudo_dir =
'/home/user/user/espresso-5.0.1/espresso-5.0.1/pseudo/' ,
                      prefix = 'QE_H_atom_Orbital_2' ,
                   verbosity = 'high' ,
                     tstress = .false. ,
                     tprnfor = .false. ,
                     tefield = .false. ,
                    dipfield = .false. ,
                    lelfield = .false. ,
 /
 &SYSTEM
                       ibrav = 8,
                           A = 20.0 ,
                           B = 20.0 ,
                           C = 45.0 ,
                         nat = 1,
                        ntyp = 1,
                     ecutwfc = 26 ,
                     ecutrho = 156 ,
                        nbnd = 228,
                 occupations = 'smearing' ,
         starting_spin_angle = .true. ,
                     degauss = 0.003675 ,
                    smearing = 'gaussian' ,
                       nspin = 1 ,
                         nr1 = 36 ,
 /
 &ELECTRONS
            electron_maxstep = 2000,
                    conv_thr = 1.D-6 ,
                 mixing_mode = 'plain' ,
                 mixing_beta = 0.05 ,
 /
ATOMIC_SPECIES
    H    1.00000  H.pz-rrkjus.UPF
ATOMIC_POSITIONS angstrom
    H     10.000000000   10.000000000   22.500000000
K_POINTS gamma


[2] pp.x input
[a] 1st ILDOS
&INPUTPP
                      prefix = 'QE_H_atom_Orbital_2' ,
                      outdir = '/home/user/tmp' ,
                     filplot = '1st_QE_H_atom_Orbital_2' ,
                    plot_num = 10,
                        emin = -6.4009 ,
                        emax = -6.3009 ,
 /
 &PLOT
                       nfile = 1 ,
                   weight(1) = 1.0,
                       iflag = 3 ,
               output_format = 5 ,
 /


[b] 2nd ILDOS
&INPUTPP
                      prefix = 'QE_H_atom_Orbital_2' ,
                      outdir = '/home/user/tmp' ,
                     filplot = '2nd_QE_H_atom_Orbital_2' ,
                    plot_num = 10,
                        emin = -0.2168 ,
                        emax = -0.1168 ,
 /
 &PLOT
                       nfile = 1 ,
                   weight(1) = 1.0,
                       iflag = 3 ,
               output_format = 5 ,
 /


[c]10th ILDOS
&INPUTPP
                      prefix = 'QE_H_atom_Orbital_2' ,
                      outdir = '/home/user/tmp' ,
                     filplot = '10th_QE_H_atom_Orbital_2' ,
                    plot_num = 10,
                        emin = 0.1896 ,
                        emax = 0.2896 ,
 /
 &PLOT
                       nfile = 1 ,
                   weight(1) = 1.0,
                       iflag = 3 ,
               output_format = 5 ,
 /
*************************
Kind regards,
Higuchi

***************************
Toshiharu Higuchi
Yokohama, Japan
***************************

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