Computational Study of Nanomaterials Invoking DFT Based Descriptors Prabhat Ranjan1, Tanmoy Chakraborty*2, Ajay Kumar3 1- Dept. of Electronics & Communication, 2*-Dept. of Chemistry, 3- Dept. of Mechatronics Manipal University Jaipur
Introduction
Result
Material doped semiconductors (Figure 1) are extensively used as Nano-clusters for their manifold application. The band gap of material doped semiconductor is an important parameter for predicting its physico-chemical properties. In this venture, we have studied 11 material doped semiconductors in terms of DFT based descriptors. These instant material doped semiconductors are choosen for its applications in the field of photovoltaics and thermoelectrics. A nice correlation has been made between experimental property and our computed descriptors.
Species
Expt. (eV)
Electronegativity (eV)
Hardness (eV)
Softness (eV)
Electrophilicity Index (eV)
InP
1.42
3.744
1.141
0.438
1.872
InAs
0.41
3.869
1.121
0.446
1.935
ZnSe
2.83
2.187
3.227
0.155
1.094
ZnS
3.84
5.429
0.225
2.227
2.715
ZnTe
2.39
3.185
2.069
0.241
1.593
CdS
2.58
3.182
2.042
0.245
1.592
CdSe
1.85
3.121
1.997
0.251
1.561
CuAlS2
3.46
4.022
0.770
0.649
2.011
CuGaS2
2.50
3.694
0.323
1.551
1.845
CuInS2
1.55
4.956
1.039
0.481
2.477
CuAlSe2
2.65
5.061
0.983
0.509
2.531
CuGaSe2
1.67
4.598
0.441
1.134
2.293
Table 1: A Collection of computed Global Descriptors along with Experimental Band Gap of a series of Semiconductors.
Figure 1. Material doped semiconductor InP and InAs.
Methodology Optimization of the structures of instant Nanomaterials have been performed using DFT methodology in terms of Local Density Approximation (LDA),with restricted spin using double zeta basis set (DZ). From the optimized geometries some important conceptual DFT based descriptors viz. Global Hardness (η), Global Softness (S), Global Electrophilicity Index (ω) and Global Electronegativity (χ) have been calculated.
Discussion
A nice correlation is established between experimental band-gap with our computed descriptors. Our evaluated hardness runs hand in hand with experimental band gap of semiconductor. Only exceptions are observed for ZnS, CuAlSe2 and CuInSe2 Another striking fact is observed in the case of ZnS. The band gap of ZnS is the highest among the instant semiconductor and that existing band gap can be nicely correlated in terms of the highest electronegativity of the compound semiconductor.
Acknowledgement One of the authors,Mr. Prabhat Ranjan expresses his acknowledgement to Mr. Sunil Chawla for providing the computational facility, ADF software package. All of the authors are thankful to the management of Manipal University Jaipur for providing the research facility.
Figure 2. Electro density distribution at HOMO and LUMO of CuInS2 molecule