Thanomngam, Pitiporn
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Preferred name
Thanomngam, Pitiporn
Alternative Name
Thanomngam, P.
Thanomngam, Pittiporn
Main Affiliation
Email
pitiporn.th@kmitl.ac.th
9 results
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Item type:Publication, First-Principles Investigation on Structural and Electronic Properties of Ferromagnetic Fe2P4O12(2015-06-23); Structural and electronic properties of Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf> have been investigated using first-principles calculation technique. The results indicated that the Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf> structure is monoclinic of C<inf>2</inf>/c with lattice parameters of a = 12.228 Å, b = 8.530 Å, c = 9.835 Å and β = 118.67°. Two nonequivalent octahedral FeO<inf>6</inf> from the calculation have an average Fe-O distance of 2.143 Å. Both FeO<inf>6</inf> are dominated by covalent interactions assigned to Fe<inf>3d</inf> and O<inf>2p</inf> at the valent electronic states. The DOS calculation gives well explanation on its half-metallic ferromagnetic property. These results are in very good agreement with the previous experimental reports. © 2015 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Pressure Dependence of Structural and Elastic Properties of Na2O: First-Principles Calculations(2022-01-01); The effect of high pressures, up to 40 GPa, on the structural and elastic properties of sodium oxide in cubic structure (c-Na<inf>2</inf>O) were investigated by first-principles calculations. The generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional was employed in the calculations. The calculated structural and elastic properties at zero pressure are consistent with the available results. The pressure dependence of structural and elastic properties was presented and discussed in detail. Under pressure, the elastic constants satisfy the Born criteria, indicating that c-Na<inf>2</inf>O is mechanically stable. Moreover, other elastic properties such as bulk modulus (B), shear modulus (G), and Young's modulus (E) under pressures were analyzed. Furthermore, the B/G values tend to increase with the increasing pressure, which means that pressure can improve the ductility of c-Na<inf>2</inf>O. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles study of antisite defects in orthorhombic PbZrO 3(2014-09-02); T-Thienprasert, JirarojFirst-principles calculations based on density functional theory (DFT) within local density approximation were employed to investigate the antisite defects, including Pb<inf>Zr</inf> and Zr<inf>Pb</inf>, in orthorhombic PbZrO<inf>3</inf> by determining their defect formation energies. The formation energies of antisite defects were then compared with those of other dominant defects, i.e., lead Pb, zirconium Zr, and oxygen O vacancies to examine the likelihood of their existence. Our results revealed that Pb<inf>Zr</inf> defect in neutral charge state is the most dominant defect under O-rich or oxidizing condition in agreement with the previous work. In addition, there is a little structural relaxation when the Zr atom is replaced by Pb atom to form Pb <inf>Zr</inf> defect in neutral charge state. In opposite, under O-poor or reducing condition, the formation energies of antisite defects are quite high and higher than those of vacancy defects. This suggests that antisite defects are unlikely to form under reducing condition. © 2014 Taylor & Francis Group, LLC. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles study of Bi and Al in orthorhombic PbZrO3(2016-04-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of pressure on structural and elastic properties of SnSe: First-principles calculations(2022-02-01); ; Limpijumnong, SukitSelected structural and elastic properties of an orthorhombic SnSe at an ambient pressure and under high pressures were investigated using first-principles calculations. At ambient pressure, the calculated structural parameters and elastic constants show a good agreement with previously reported values. Effects of pressure on structural and elastic properties were presented and discussed in detail. Moreover, the pressure dependence of selected structural and elastic properties, which relate to phase transition from an orthorhombic phase to the high-pressure phase, was analyzed. We suggested that the phase transition is related to the compression along the c- and b-axis which correspond to C<inf>33</inf> and C<inf>22,</inf> respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Hybrid Functional Calculation of Defects in Pseudo-binary Indium Oxynitride(2016-06-01); Indium oxynitride (InO<inf>x</inf>N<inf>y</inf>) is an attractive material that shows multi-functionality in electronic and optical applications due to its wide range tunable band gap. However there were only few studies available for this interesting material, especially on defect structure. In this work, first-principles calculation based on Density Functional Theory (DFT) within the Heys, Scuseria and Ernzerhof (HSE) hybrid functional for exchange-correlation energy was performed to investigate atomic structure, electronic properties and role of oxygen (O) defects occurred by means of their defect formation energies. The defect formation energies of both oxygen defects were compared with all possible native point defects in indium nitride. Our results revealed that O atom prefers to substitute in N site since it has lowest formation energy for all equilibrium crystal growth conditions. This result is consistent with the experimental observations by RF magnetron sputtering method. Moreover, the energy gap of indium nitride calculated by HSE method is 0.710 eV. The HSE calculation showed that the O antisite slightly widening the indium nitride band gap to 0.766 eV while the N vacancy gives wider indium nitride band gap of 1.410 eV. The complex defects of N vacancy and O antisite were also performed and discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of exchange-correlation and GW approximations on electrical property of cubic, tetragonal and orthorhombic CH3NH3PbI3(2017-01-02); A first-principle calculations based on van der Waals-corrected Density Functional Theory (vdW-DFT) is performed to investigate atomic structure of methyl ammonium lead iodine (CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf>) which is a key material for high efficiency solid-state solar cell. A temperature dependent symmetry was previously reported which also included in this study. DFT calculation of electronic and optical properties are systematically studied with semi-local, non-local exchange-correlation and post-DFT approximation including PBE, HSE06 hybrid functional and GW. Relativistic effect in lead ion was taken into account by incorporating spin-orbit coupling (SOC) effect to obtain more accurate band gap of this material. With GW-SOC functional, our results of band gap calculations showed good agreement between DFT calculations and experimental studies which confirmed that this computational scheme is suitable for high accuracy material design, e.g. for solar cell applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, XAFS analysis of indium oxynitride thin films grown on silicon substrates(2013-01-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First principles calculations on crystal and electronic structure of Co2P4O12(2014-09-02); Crystal and electronic structure of violet-pink Co<inf>2</inf>P <inf>4</inf>O<inf>12</inf> have been investigated using first principles calculations based on density functional theory. Its theoretical X-ray diffraction and X-ray absorption fine structure spectra were calculated and compared with their experimental spectra to verify its monophasic. The calculated spectra are in good agreement with the experimental data giving parameters of a = 11.993 Å, b = 8.328 Å, c = 10.150 Å and β = 118.51°. Our calculations on band structure and density of states of Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> showed that its major electronic transition is associated with internal Co-3d. The calculations indicated that Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> is a half metal ferromagnetic material which disagreed with the experimental knowledge. © 2014 Taylor & Francis Group, LLC.1