scholarly journals Chemical bonding and Born charge in 1T-HfS2

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
S. N. Neal ◽  
S. Li ◽  
T. Birol ◽  
J. L. Musfeldt
Keyword(s):  
Chemical Bonding ◽  
First Principles ◽  
Ionic Crystal ◽  
Unit Cell Volume ◽  
Vibrational Mode ◽  
Transition Metal Dichalcogenide ◽  
First Principles Calculations ◽  
Mass Unit ◽  
Local Charge ◽  
Born Effective Charge

AbstractWe combine infrared absorption and Raman scattering spectroscopies to explore the properties of the heavy transition metal dichalcogenide 1T-HfS2. We employ the LO–TO splitting of the Eu vibrational mode along with a reevaluation of mode mass, unit cell volume, and dielectric constant to reveal the Born effective charge. We find $${Z}_{{\rm{B}}}^{* }$$ Z B *  = 5.3e, in excellent agreement with complementary first-principles calculations. In addition to resolving the controversy over the nature of chemical bonding in this system, we decompose Born charge into polarizability and local charge. We find α = 5.07 Å3 and Z* = 5.2e, respectively. Polar displacement-induced charge transfer from sulfur p to hafnium d is responsible for the enhanced Born charge compared to the nominal 4+ in hafnium. 1T-HfS2 is thus an ionic crystal with strong and dynamic covalent effects. Taken together, our work places the vibrational properties of 1T-HfS2 on a firm foundation and opens the door to understanding the properties of tubes and sheets.

First-Principles Study on the Clean and Nb Doped TiO2(110)γ-TiAl(111) Interfaces

2012 ◽  
Vol 602-604 ◽  
pp. 555-558 ◽  
Author(s):  
Hui Nan Hao ◽  
Xu Wang ◽  
Fu He Wang
Keyword(s):  
Structural Stability ◽  
Density Of States ◽  
Chemical Bonding ◽  
First Principles ◽  
Adhesion Energy ◽  
First Principles Calculations ◽  
First Principles Study

In this paper, the structural stability, adhesion and chemical bonding of the TiO2 (110)/TiAl (111) interface are investigated by the first-principles calculations. We predict the maximum adhesion energy of 1.91J/m2 of the TiO2/TiAl interface. We also calculated the Nb doped interface, and found that the doped Nb atom prefers to replace the Ti atom at the second layer of TiAl slab. The atomic geometry and density of states are analyzed. The results show that the effect of doped Nb is localized and insignificant on the TiO2 (110)/TiAl(111) interface.

Unifying Chemical Bonding Models for Boranes

2007 ◽  
Vol 1038 ◽  
Author(s):  
Mao-Hua Du ◽  
Susumu Saito ◽  
S. B. Zhang
Keyword(s):  
Coordination Number ◽  
Triangular Lattice ◽  
Chemical Bonding ◽  
First Principles ◽  
First Principles Calculations ◽  
Cage Structure ◽  
Boron Hydrides

AbstractWe demonstrate, based on first-principles calculations, that chemical bonding in deltahedral boron hydrides, BnHn2− also known as closo boranes, can be understood within the three-center two-electron (3c2e) bonding model in line with other families of boranes. We show that bonding in the triangular lattice of BnHn2− cages can be described by delocalized resonant 3c2e bonding. We also find that the reason for all the BnHn2− to be dianions can be attributed to the reduction of boron coordination number in the deltahedral cage structure from that of boron sheet with triangular lattice.

scholarly journals The role of Anderson’s rule in determining electronic, optical and transport properties of transition metal dichalcogenide heterostructures

2018 ◽  
Vol 20 (48) ◽  
pp. 30351-30364 ◽  
Author(s):  
Ke Xu ◽  
Yuanfeng Xu ◽  
Hao Zhang ◽  
Bo Peng ◽  
Hezhu Shao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transition Metal ◽  
Transport Properties ◽  
First Principles ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenide ◽  
First Principles Calculations

We have investigated the structure and electronic, mechanical, transport and optical properties of van der Waals transition metal dichalcogenide heterostructures using first-principles calculations.

Chemical Bonding and Pseudogap in Zn- and Cd-based Compounds with Complex Hexagonal Structures

2003 ◽  
Vol 805 ◽  
Author(s):  
Y. Ishii ◽  
K. Nozawa ◽  
T. Fujiwara
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
Chemical Bonding ◽  
First Principles ◽  
Electronic Structures ◽  
Unit Cell ◽  
First Principles Calculations ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Crystal Orbital

ABSTRACTElectronic structures of hexagonal Zn-Mg-Y and Cd58Y13 compounds are studied by first-principles calculations. Both of the systems show deep pseudogap in the electronic density of states near the Fermi level and considered to be stabilized electronically. To illustrate bonding nature of electronic wavefunctions, the crystal orbital Hamilton population (COHP) is calculated for neighboring pairs of atoms in the unit cell. It is found that the bonding nature is changed from bonding to anti-bonding almost exactly at the Fermi level for Zn-Zn and Cd-Cd bonds. On the contrary, for Zn/Cd-Y bonds, both of the states below and above the pseudogap behave as bonding ones. Possible effects of the p-d hybridization are discussed.

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