Local work functions of clean tungsten surfaces under electric fields based on ab initio calculations

2019 ◽  
Author(s):  
Yue Wang ◽  
Liangliang Xu ◽  
Ming-Chieh Lin ◽  
Tsan-Chuen Leung
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electric Fields ◽  
Work Functions ◽  
Local Work

scholarly journals Critical Evaluation of Various Spontaneous Polarization Models and Induced Electric Fields in III-Nitride Multi-Quantum Wells

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4935
Author(s):  
Ashfaq Ahmad ◽  
Pawel Strak ◽  
Kamil Koronski ◽  
Pawel Kempisty ◽  
Konrad Sakowski ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Quantum Wells ◽  
Ab Initio ◽  
Electric Fields ◽  
Spontaneous Polarization ◽  
Berry Phase ◽  
Critical Evaluation ◽  
Theoretical Data ◽  
Polarization Difference ◽  
Binary Compounds

In this paper, ab initio calculations are used to determine polarization difference in zinc blende (ZB), hexagonal (H) and wurtzite (WZ) AlN-GaN and GaN-InN superlattices. It is shown that a polarization difference exists between WZ nitride compounds, while for H and ZB lattices the results are consistent with zero polarization difference. It is therefore proven that the difference in Berry phase spontaneous polarization for bulk nitrides (AlN, GaN and InN) obtained by Bernardini et al. and Dreyer et al. was not caused by the different reference phase. These models provided absolute values of the polarization that differed by more than one order of magnitude for the same material, but they provided similar polarization differences between binary compounds, which agree also with our ab initio calculations. In multi-quantum wells (MQWs), the electric fields are generated by the well-barrier polarization difference; hence, the calculated electric fields are similar for the three models, both for GaN/AlN and InN/GaN structures. Including piezoelectric effect, which can account for 50% of the total polarization difference, these theoretical data are in satisfactory agreement with photoluminescence measurements in GaN/AlN MQWs. Therefore, the three models considered above are equivalent in the treatment of III-nitride MQWs and can be equally used for the description of the electric properties of active layers in nitride-based optoelectronic devices.

Millimetre-wave and infrared spectroscopy of Br13 CN: anharmonic force field of cyanogen bromide from spectroscopic data and ab initio calculations

1997 ◽  
Vol 90 (3) ◽  
pp. 495-497
Author(s):  
CLAUDIO ESPOSTI ◽  
FILIPPO TAMASSIA ◽  
CRISTINA PUZZARINI ◽  
RICCARDO TARRONI ◽  
ZDENEK ZELINGER
Keyword(s):  
Infrared Spectroscopy ◽  
Force Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Spectroscopic Data ◽  
Cyanogen Bromide ◽  
Millimetre Wave ◽  
Anharmonic Force
Sign in / Sign up

Export Citation Format

Share Document