Hi all
I want to calculate band gap of a perovskite structure at different pressures, first I did cell optimization of different pressures, then I used optimized lattice constant and relaxed atomic coordinates as inputs to calculate band gap
As it's known band gap should increase with increasing pressure, but from pressure 1 Gpa to 5 Gpa , my band gaps decreasing, my question is:
Is this a correct way to calculate pressure dependence band gap? if no , what method I should use in abinit? if yes why this is happening with me?
regards
Nawzad
pressure dependence of band gap [SOLVED]
Moderators: gmatteo, bruneval, rigna
pressure dependence of band gap
 Attachments

 pressure+.in
 Input for optimization in different pressures
 (1.1 KiB) Downloaded 198 times

 CsPbCl3B3LPY.out
 Output
 (541.52 KiB) Downloaded 156 times

 CsPbCl3B3LPY.in
 Input for band gap at 1 Gpa pressure
 (1.25 KiB) Downloaded 157 times

 pressure+.out
 Output
 (177.05 KiB) Downloaded 158 times
Re: pressure dependence of band gap [SOLVED]
Dear Nawzad,
I would say that the band gap will have the tendency to reduce with pressure in general, no? But I might be wrong, do you have references that show increase of the band gap under pressure in perovskites? Of course this could depend on the system...
Best wishes,
Eric
I would say that the band gap will have the tendency to reduce with pressure in general, no? But I might be wrong, do you have references that show increase of the band gap under pressure in perovskites? Of course this could depend on the system...
Best wishes,
Eric
Re: pressure dependence of band gap
Dear Eric
Yes band gap reduces with increasing of pressure...but I have seen in references, for example, for CsPbI3 phase transition happens from cubic to orthohombic before 0.4 Gpa, But I have increased pressure up to 1 Gpa,
my question is, How I know when phase changes in abinit?
Thanks for replying and help
Nawzad
Yes band gap reduces with increasing of pressure...but I have seen in references, for example, for CsPbI3 phase transition happens from cubic to orthohombic before 0.4 Gpa, But I have increased pressure up to 1 Gpa,
my question is, How I know when phase changes in abinit?
Thanks for replying and help
Nawzad
Re: pressure dependence of band gap
Dear Nawzad,
calculate total energy as a function of pressure for both cubic and orthorhombic structures.
there will be crossover at some pressure (you said experimental one is 0.4GPa).
You have to use the bandgaps corrosponding to minimum energy structure at each pressure.
regards
rajaraman
calculate total energy as a function of pressure for both cubic and orthorhombic structures.
there will be crossover at some pressure (you said experimental one is 0.4GPa).
You have to use the bandgaps corrosponding to minimum energy structure at each pressure.
regards
rajaraman
Re: pressure dependence of band gap
rajaraman wrote:Dear Nawzad,
calculate total energy as a function of pressure for both cubic and orthorhombic structures.
there will be crossover at some pressure (you said experimental one is 0.4GPa).
You have to use the bandgaps corrosponding to minimum energy structure at each pressure.
regards
rajaraman
Dear rajaraman
Thanks a lot for the reply,,, I will try that
Regards
Nawzad
Re: pressure dependence of band gap
rajaraman wrote:Dear Nawzad,
calculate total energy as a function of pressure for both cubic and orthorhombic structures.
there will be crossover at some pressure (you said experimental one is 0.4GPa).
You have to use the bandgaps corrosponding to minimum energy structure at each pressure.
regards
rajaraman
Dear rajaraman
I have calculated total energy of cubic and tetragonal of CsPbCl3 , but it gives me same energy for both structures
any help plz?
best regards
Nawzad
 Attachments

 optimiztion.in
 (1.55 KiB) Downloaded 116 times

 optimiztion.in
 (1.39 KiB) Downloaded 114 times