[QE-users] Binding energy and interatomic force constant

[Stefano Baroni]

Here, I beg to differ. The binding is defined as the energy necessary to bring all the atoms from their equilibrium position (Δx=0) to an infinite distance from each other  (Δx=\infty). In any harmonic model, evidently, this energy would be infinite. The problem is, the harmonic model, within which interatomic force constants are defined, is only meaningful in the neighbourhood of the equilibrium position and does not say anything about the forces acting on atoms far from it. Hope this clarifies a bit. Stefano B

On 26 Mar 2024, at 18:51, Mpayami via users <users at lists.quantum-espresso.org> wrote:

Dear Krishnendu,

Hi.
I add a few words to Prof. Stefano Baroni's reply:
Suppose you have a harmonic spring obeying Hook's law, for which the stored energy is E=K*(Δx)^2/2.
Here, K plays the role of interatomic force constant. As you see, just knowing K one can not calculate
the stored energy unless on knows the value of Δx.

Bests

-------------------------------
Mahmoud Payami
NSTRI, AEOI,Tehran, Iran
Email: mpayami at aeoi.org.ir
Phone: +98(0)2182066504
------------------------------------

----- Original Message -----
________________________________
From: Stefano Baroni (baroni at sissa.it<mailto:baroni at sissa.it>)
Date: 06/01/1403 11:41
To: Quantum ESPRESSO users Forum (users at lists.quantum-espresso.org<mailto:users at lists.quantum-espresso.org>)
Subject: Re: [QE-users] Binding energy and interatomic force constant

No. SB

___
Stefano Baroni, Trieste -- http://stefano.baroni.me<http://stefano.baroni.me/>

On 25 Mar 2024, at 07:15, KRISHNENDU MUKHERJEE <krishnendu at nmlindia.org<mailto:krishnendu at nmlindia.org>> wrote:



Dear all,

 Can I compute the binding energy of a nano-crystal from the interatomic force constant ?

Thanking you,
Best regards,
Krishnendu



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and economic cooperation amongst peoples
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Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>)
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people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
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Stefano Baroni - Trieste —  http://stefano.baroni.me




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