Density functional theory calculation of 2p spectra of SiH₄, PH₃, H₂S, HCl, and Ar

Abstract

ABSTRACT:The method developed recently for prediction of 1s electron spectra is now extended to the 2p spectra of SiH 4 , PH 3 , H 2 S, HCl, and Ar. The method for X-ray absorption spectra involves the use of ⌬E for the excitation and ionization energies, and application of timedependent density functional theory using the exchange-correlation potential known as statistical average of orbital potentials for the intensities. Additional assumptions and approximations are also made. The best exchange-correlation functional E xc for the earlier calculation of ⌬E in 1s spectra of C to Ne (namely Perdew-Wang 1986 exchange, combined with Perdew-Wang 1991 correlation) is no longer used in this work on 2p spectra of Si to Ar. Instead, recently tested E xc good for 2p core-electron binding energies (known as OPTX) for exchange and LYP for correlation, plus scalar zeroth-order regular approximation is adopted here for the ⌬E calculations. Our calculated X-ray absorption spectra are generally in good agreement with experiment. Although the predictions for the higher excitations suffer from basis set difficulties, our procedure should be helpful in the interpretation of absorption spectra of 2p electrons of Si to Ar. In addition, we report calculated results for other kinds of electron spectra for SiH 4 , PH 3 , H 2 S, HCl, and Ar, including valence electron ionizations and excitations as well as X-ray emission.

K- and L-edge X-ray absorption spectrum calculations of closed-shell carbon, silicon, germanium, and sulfur compounds using damped four-component density functional response theory

“…46 In terms of relative intensities, it is to be noted that the lowest a 1 peak, corresponding to excitations from 2p 3/2 , is significantly less intense than the second peak due to transitions from 2p 1/2 , and it is clearly not possible to rely on a statistical distribution of intensity. 53 This counterintuitive trend, deviating from the 2 : 1 statistical ratio of electron population of subshells, is observed for all silane derivatives in the present study. Such non-statistical intensity ratios have been observed for numerous systems, and these have been attributed to a sensitive balance between core-hole spin-orbit and electron-hole exchange interactions 7,17,25,42,44 -in the independent-particle approximation only core-hole spin-orbit interactions would be in effect, and the ratio would thus be 2 : 1.…”

“…The experimental spectra of these molecules are well investigated, especially for the L 2,3 -edges [37][38][39][40][41][42][43][44][45][46][47][48][49] where vibrationally resolved spectra are available, 45,46,48,49 but a number of experimental studies on the L 1 -edge [38][39][40][41][42][43] and the K-edge 50,51 are also found in the literature. From a theoretical standpoint, X-ray absorption spectra have traditionally been interpreted using variations of the Xa method and configuration interaction, 37,51,52 but more recent TDDFT results for SiH 4 53 and SiF 4 54 are also available.…”

Core-Level 2s and 2p Binding Energies of Third-Period Elements (P, S, and Cl) Calculated by Hartree–Fock and Kohn–Sham ΔSCF Theory

“…The 2s and 2p core level electron spectra of the third-period elements were studied experimentally by X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). Theoretically, Chong et al calculated 2p spectra of SiH 4 , PH 3 , H 2 S, HCl, and Ar by KS density functional theory (DFT). Their calculated XAP for 2p ionization is generally in good agreement with the experiment.…”

“…The 2s and 2p core level electron spectra of the third-period elements were studied 25 experimentally by X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). Theoretically, Chong et al 41 In previous studies, 36,37 we studied the 1s core ionization energies of second-and third-period elements by using HF and KS SCF theory. We used ΔSCF, STS, and two corrected STS methods [termed shifted STS (1) and shifted STS (2), to accurately reproduce ΔSCF and the experiment, respectively].…”

Estudo de energias de dupla ionização e de ligação de elétron por Monte Carlo Quântico e métodos pós-hartree-fock

“…O método apresenta resultados excelentes, que diferem dos valores experimentais por menos de 0,2 eV. [43][44][45][46][47][48] Além das energias de ionização de caroço, recentemente o método de Chong têm sido utilizado para determinar energias de dupla ionização de valência de uma série dé atomos e moléculas 49 , mostrando boa precisão. Entretanto, os métodos baseados na Teoria do Funcional de Densidade formalmente não são capazes de tratar estados excitados, o que pode nos direcionar a descartar de imediato o seu uso no cálculo de energias de ionização.…”