[Wien] Query regarding elastic constants of SnSe2

[Fecher, Gerhard]

You just did not read and understand my e-mail

c66 = (c11-c12)/2 in hexagonal structures

the required coefficent c14 for the C6 (CdI2) structure is not calculated by IRElast !!

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Physics
Johannes Gutenberg - University
55099 Mainz
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von shamik chakrabarti [shamik15041981 at gmail.com]
Gesendet: Samstag, 10. August 2024 15:18
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] Query regarding elastic constants of SnSe2

Dear Sir,

           Initially the structure was optimized with nlvdw and spin polarization to check Ca intercalation voltage in it. Promising results were found. However, during elastic properties calculation I have taken the optimize structure a priori and run the command run_lapw. I guess, even if the initial structure was for spin polarized for non spin polarize calculation it should get the optimized structure while using the command run_lapw -ec 0.0001 -cc 0.0001 -fc 1.0 -min...what is your advice in this regard?


On Sat, 10 Aug 2024 at 18:43, Laurence Marks <laurence.marks at gmail.com<mailto:laurence.marks at gmail.com>> wrote:
Please read your email carefully, and use the computer behind your eyes.

"optimized by using spin polarization and nlvdw"
"running command; run_lapw ..."

Are these the same?
___
Professor Laurence Marks (Laurie)
Department of Materials Science and Engineering, Northwestern University
www.numis.northwestern.edu<http://www.numis.northwestern.edu>
"Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Györgyi

On Sat, Aug 10, 2024, 07:50 shamik chakrabarti <shamik15041981 at gmail.com<mailto:shamik15041981 at gmail.com>> wrote:
Dear Sir,

           I have used the optimized structure of SnSe2, which is optimized by using spin polarization and nlvdw. Now, this optimized file is used as an input for set_elast_lapw. I have used the running command; run_lapw -ec 0.0001 -cc 0.0001 -fc 1.0 -min

I have obtained the following values of elastic constants; c11=90.8145, c12=23.8215, c13=18.9015, c33=21.961 & c55=4.368 (I have considered fit 2)

However, the elastic constants reported in the literatures are;c11=111, c12=33.39, c13=33.08, c33 = 22.63, c44=44.48, c66= 38.80

Please advice.

with regards,



On Sat, 10 Aug 2024 at 17:14, morteza jamal <m_jamal57 at yahoo.com<mailto:m_jamal57 at yahoo.com>> wrote:
When the sensitivity of elastic constant calculations ignores with respect to the order of fit.

However from view point of theory, when the strain is small ( very small) , the optimized value for order of fit is 2.

IRelast package checks sensitivity of elastic constants calculations  to the order of fit and prints them.


--
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India
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--
Dr. Shamik Chakrabarti
Research Fellow
Department of Physics
Indian Institute of Technology Patna
Bihta-801103
Patna
Bihar, India