Top Page > Browsing Calculation of the electronegativity of a periodic system Date: 2023/05/30 10:06 Name: Masanobu Miyata   Dear Ozaki-sensei, From the OpenMX manual, I understand how to calculate the ionization potential and electron affinity of an isolated system. When calculating the electronegativity of a periodic system, I should not use the delta-SCF and exact Coulomb cutoff methods for normal periodic structures, but only consider charge addition and subtraction by scf.system.charge and spin polarization, right?Best regards,Miyata Page: Re: Calculation of the electronegativity of a periodic system ( No.1 ) Date: 2023/05/30 14:13 Name: T. Ozaki Hi, Do you mean by the electronegativity, A,  the following definition?A = E(N) − E(N+1)If so, in the GGA and LDA functionals the quantity for bulk must be equivalent to the conduction band minimum (CBM) given by the KS eigenvalue. The way you metioned:"only consider charge addition and subtraction by scf.system.charge and spin polarization"does not work, since an additonanal energy term is included by the interaction with the compesation background charge.The method:"the delta-SCF and exact Coulomb cutoff methods"also does not work, since the method is valid for a localized state.An electron added to a bulk tends to be delocalized, and the situation violates the conditionthat "the delta-SCF and exact Coulomb cutoff methods" is valid. Even if we apply the method to a super cell being large enough, we will see that E(N+1) - E(N) is equivalent to the CBM. The issue is closely related to the underestimation of the fundamental gap by LDA and GGA.Note that the fundamental gap is given by Egap = I - A, where I = E(N−1) − E(N),  A = E(N) − E(N+1).Regards, TO  Re: Calculation of the electronegativity of a periodic system ( No.2 ) Date: 2023/05/30 14:29 Name: Masanobu Miyata  Dear Ozaki-sensei,Thank you very much for your prompt reply.　Sorry.The definition of electronegativity was ambiguous.　The electronegativity I am talking about is Mulliken's electronegativity (average value of electron affinity and ionization energy).First ionization energy: E(N+1) - E(N)  Electron affinity: E(N) - E(N-1)E(N): Nuetral, scf.SpinPolarization offE(N+1): scf.system.charge = 1, scf.SpinPolarization  onE(N-1): scf.system.charge = -1, scf.SpinPolarization  onThen, the electronegativity of Mulliken is as follows.　{E(N+1)-E(N-1)}/2In this case, is the guarantee of the background charge still not cancelled?Best regards,Miyata  Re: Calculation of the electronegativity of a periodic system ( No.3 ) Date: 2023/05/31 11:24 Name: T. Ozaki Hi, Even if the calculations of E(N+1) and E(N-1) are properly performed, we must obtain that (E(N+1) - E(N) + E(N) - E(N-1))/2 = (ep_VBM - ep_CBM)/2 in LDA and GGA, where ep_VBM and ep_CBM are the Kohn-Sham eigenvalues for the VBM and CBM, respectively.Regards, TO  Re: Calculation of the electronegativity of a periodic system ( No.4 ) Date: 2023/05/31 17:37 Name: Masanobu Miyata  Dear Ozaki-sensei,Thank you for your prompt reply.Best regards,Miyata Page: 

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