Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session A16: Focus Session: Materials by Theoretical Design |
Hide Abstracts |
Sponsoring Units: DMP DCOMP Chair: James Rondinelli, Northwestern University Room: 101AB |
Monday, March 2, 2015 8:00AM - 8:36AM |
A16.00001: Theory-guided discovery of new superconducting materials Invited Speaker: Aleksey Kolmogorov Extensive theoretical effort to predict new superconductors has resulted in remarkably few discoveries. Successful examples so far have been restricted primarily to pressure- or doping-driven superconducting transformations in existing materials. In this talk I will describe our work that has led to the prediction [1] and discovery [2] of a brand-new superconducting FeB4 compound with a previously unknown crystal structure. First measurements supported the predicted phonon-mediated pairing mechanism, rare for an iron-based superconductor. The identification of FeB4 candidate material was a result of combined high-throughput screening, targeted evolutionary search [3], and rational design. The systematic study of more than 12,000 metal boride phases has identified dozens of synthesizable materials with unusual structural motifs, some of which have been confirmed experimentally [4]. I will overview employed strategies for selecting promising superconducting compounds and describe our on-going work on accelerating the search for stable materials. [1] A.N. Kolmogorov \textit{et al}., Phys. Rev. Lett. 105, 217003 (2010) [2] H. Gou \textit{et al.}, Phys. Rev. Lett., 111, 157002 (2013) [3] Module for Ab Initio Structure Evolution (2009-), \underline {http://maise-guide.org} [4] A.G. Van Der Geest and A. N. Kolmogorov, CALPHAD 46, 184 (2014) [Preview Abstract] |
Monday, March 2, 2015 8:36AM - 8:48AM |
A16.00002: Guided design of copper oxysulfide superconductors Chuck-Hou Yee, Turan Birol, Gabriel Kotliar Using the framework of chemical intuition introduced by Antipov, \emph{et. al.}, in his synthesis of the Hg-based high-temperature superconductors, supplemented with modern first-principles electronic structure tools, materials databases, and evolutionary algorithms capable of exploring large configurational spaces, we design a novel family of copper oxysulfides. We explore the predictions of theories based on charge-transfer energies, orbital distillation and uniaxial strain on the superconducting transition temperatures of these oxysulfides. [Preview Abstract] |
Monday, March 2, 2015 8:48AM - 9:00AM |
A16.00003: Conformational space annealing scheme in the inverse design of functional materials Sunghyun Kim, In-Ho Lee, Jooyoung Lee, Young Jun Oh, Kee Joo Chang Recently, the so-called inverse method has drawn much attention, in which specific electronic properties are initially assigned and target materials are subsequently searched. In this work, we develop a new scheme for the inverse design of functional materials, in which the conformational space annealing (CSA) algorithm for global optimization is combined with first-principles density functional calculations. To implement the CSA, we need a series of ingredients, (i) an objective function to minimize, (ii) a 'distance' measure between two conformations, (iii) a local enthalpy minimizer of a given conformation, (iv) ways to combine two parent conformations to generate a daughter one, (v) a special conformation update scheme, and (vi) an annealing method in the 'distance' parameter axis. We show the results of applications for searching for Si crystals with direct band gaps and the lowest-enthalpy phase of boron at a finite pressure and discuss the efficiency of the present scheme. [Preview Abstract] |
Monday, March 2, 2015 9:00AM - 9:12AM |
A16.00004: Computational materials design of negative effective $U$ system in the hole-doped Delafossite of CuAlO$_{2}$, AgAlO$_{2}$ and AuAlO$_{2}$ Akitaka Nakanishi, Tetsuya Fukushima, Hiroki Uede, Hiroshi Katayama-Yoshida In order to realize the super-high-$T_{\mathrm{C}}$ superconductors ($T_{\mathrm{C}}$\textgreater 1,000K) based on the general design rules [1] for the negative $U_{eff}$ system, we have performed computational materials design for the$ U_{eff} $\textless 0 system in the hole-doped two-dimensional (2D) Delafossite CuAlO$_{2}$, AgAlO$_{2}$ and AuAlO$_{2}$ from the first principles. We find the interesting chemical trend of $T_{\mathrm{C}}$ in 2D and 3D systems; where the $T_{\mathrm{C}}$ increases exponentially in the weak coupling regime (\textbar $U_{eff}$ (-0.44eV)\textbar \textless $W$(2eV), $W$ is the band width) for hole-doped CuFeS$_{\mathrm{2}}$ [2], then the $T_{\mathrm{C}}$ goes through a maximum when \textbar $U_{eff}$ (-4.88eV, -4.14eV)\textbar $\approx \quad W$(2.8eV, 3.5eV) for hole-doped AgAlO$_{\mathrm{2}}$ and AuAlO$_{\mathrm{2}}$, and the $T_{\mathrm{C}}$ decreases with increasing \textbar $U_{eff}$\textbar in strong coupling regime, where \textbar $U_{eff}$ (-4.53eV)\textbar \textgreater $W$(1.7eV) for hole-doped CuAlO$_{2}$ \\[4pt] [1] H. Katayama-Yoshida et al., \textit{Appl. Phys. Express, }\textbf{1 }081703, 2008.\\[0pt] [2] T. Fukushima et al., \textit{J. Phys. Condens. Matter, }\textbf{26 }355502, 2014. [Preview Abstract] |
Monday, March 2, 2015 9:12AM - 9:24AM |
A16.00005: How to design negative effective $U$ Fermion system in hole doped chalcopyrite CuFeS$_2$? Hiroshi Katayama-Yoshida, Tetsuya Fukushima, Hiroki Uede, Yuki Takawashi, Akitaka Nakanishi, Kazunori Sato Here, we have proposed a general rule of the attractive Fermion system in the purely electronic origin, which is called negative effective $U$ ($U_{eff} <0$) system. Purely electronic-originated $U_{eff} <0$ is caused by (i) the exchange-correlation-induced energy gain in the Hund's rules, and (ii) the charge-excitation-induced energy gain. Based on the general design rules, we perform ab initio electronic structure calculations for hole-doped Chalcopyrite CuFeS$_2$. It is found that the hole-doped CuFeS$_2$ has the negative $U_{eff} = -0.44$ eV (-5000 K). The $U_{eff} <0$ in CuFeS$_2$ is originated by the charge-excitation- induced mechanism in the hole-doped Cu$^{2+}(d^9)$ and S$^{2-}(s^2p^5)$, and also originated by the exchange-correlation-induced mechanism in the hole-doped Fe$^{4+}(d^4)$. The hole-doped paramagnetic and metallic CuFeS$_2$ with the $U_{eff} <0$ may cause a possible super-high-$T_c$ superconductor ($T_c$ $\approx$ 1000 K, if $2\Delta/k_BT_c =10$ by assuming a strong coupling regime.) because of the strong attractive electron-electron interactions (superconducting gap $\Delta \approx |U_{eff}|\approx$ 5000 K). We propose a new computational materials design methodology to design super-high-$T_c$ superconductors starting from the atomic number only. [Preview Abstract] |
Monday, March 2, 2015 9:24AM - 9:36AM |
A16.00006: Direct band gap silicon crystals predicted by an inverse design method Young Jun Oh, In-Ho Lee, Jooyoung Lee, Sunghyun Kim, Kee Joo Chang Cubic diamond silicon has an indirect band gap and does not absorb or emit light as efficiently as other semiconductors with direct band gaps. Thus, searching for Si crystals with direct band gaps around 1.3 eV is important to realize efficient thin-film solar cells. In this work, we report various crystalline silicon allotropes with direct and quasi-direct band gaps, which are predicted by the inverse design method which combines a conformation space annealing algorithm for global optimization and first-principles density functional calculations. The predicted allotropes exhibit energies less than 0.3 eV per atom and good lattice matches, compared with the diamond structure. The structural stability is examined by performing finite-temperature ab initio molecular dynamics simulations and calculating the phonon spectra. The absorption spectra are obtained by solving the Bethe-Salpeter equation together with the quasiparticle $G_{0}W_{0}$ approximation. For several allotropes with the band gaps around 1 eV, photovoltaic efficiencies are comparable to those of best-known photovoltaic absorbers such as CuInSe$_{2}$. [Preview Abstract] |
(Author Not Attending)
|
A16.00007: Design of I$_{2}$-II-IV-VI$_{4}$ Semiconductors through Element-substitution: the Thermodynamic Stability Limit and Chemical Trend Shiyou Chen, Congcong Wang, Hongjun Xiang, Xin-Gao Gong, Aron Walsh, Su-Huai Wei Through element substitution in kesterite Cu$_{2}$ZnSnS$_{4}$ or Cu$_{2}$ZnSnSe$_{4}$, a class of I$_{2}$-II-IV-VI$_{4}$ semiconductors can be designed as novel functional materials. Using the first-principles calculations, we show that this element-substitution design is thermodynamically limited, i.e., although I$_{2}$-II-IV-VI$_{4}$ with I$=$Cu, Ag, II$=$Zn, Cd, Hg, IV$=$Si, Ge, Sn and VI$=$S, Se, Te are stable quaternary compounds, those with II$=$Mg, Ca, Sr, Ba, IV $=$Ti, Zr, Hf, and VI$=$O are unstable against the phase-separation into the competing binary and ternary compounds. Three main phase-separation pathways are revealed. In general, we show that if the secondary II-VI or I$_{2}$-IV-VI$_{3}$ phases prefer to have non-tetrahedral structures, then the I$_{2}$-II-IV-VI$_{4}$ semiconductors tend to phase separate. This finding can be used as a guideline for future design of new quaternary semiconductors. [Preview Abstract] |
Monday, March 2, 2015 9:48AM - 10:00AM |
A16.00008: Materials predicted to be topological insulators in hypothetical structures assumed by theorists might be trivial insulators in their stable phases Giancarlo Trimarchi, Xiuwen Zhang, Alex Zunger The quest for new topological insulators (TIs) has motivated numerous {\em ab initio} calculations of the topological metric $Z_{2}$ of candidate compounds in hypothetical crystal structures, or in assumed pressure or doping conditions. However, TI-ness might destabilize certain crystal structures that would be replaced by other structures, which might not be TIs. Here, we discuss such false-positive predictions recurrent in the {\em ab initio} search for new TIs: (i) Various ABX compounds, predicted to be TIs in the assumed ZrBeSi-type structure that turns out to be unstable, become trivial insulators in their stable structures. (ii) Band-inversion-inducing structure perturbations destabilize the system which is instead trivial at equilibrium: examples of this scenario are the cubic $A^{\textrm{III}}$BiO$_{3}$ perovskites that transform from topological to trivial when they relax to their equilibrium structures. (iii) Doping destabilizes the band-inverted system that relaxes to a trivial atomic configuration (orthorhombic band-inverted BaBiO$_{3}$ becomes trivial upon electron doping). This shows the need of performing total energy along with $Z_{2}$ calculations to predict stable TIs. [Preview Abstract] |
Monday, March 2, 2015 10:00AM - 10:12AM |
A16.00009: Doping designed half-Heusler insulators Yonggang Yu, Xiuwen Zhang, Liping Yu, Feng Yan, A. Nagaraja, T. O. Mason, Alex Zunger The 18-valence-electron 1:1:1 compounds of the type III-X-V, IV-X-IV, IV-IX-V and V-IX-IV include thermoelectric materials, topological insulators, and recently a high mobility p-type transparent conductor TaIrGe (arXiv:1406.0872), yet their intrinsic doping trends are poorly known or understood. Using the ``modern theory of doping'' that addresses via DFT and HSE the thermodynamic formation energies and the DFT-corrected transition levels in the gap, we find the following interesting trends: (1) High atomic number compounds such as TaIrGe made of metallic elements can surprisingly have a large band gap (direct) of $\sim$ 2.5 eV. (2) Half-Heusler such as A$^{\mathrm{(IV)}}$B$^{\mathrm{(X)}}$C$^{\mathrm{(IV)}}$ is naturally n-type if its DFT calculated chemical stability field resides within the A-rich or B-rich domain of the stability triangle, while it is p-type if it resides within the C-rich domain. Such calculations provide a good metric. (3) When the B atom [at (1/4,1/4,1/4)] is as large as Ir or Pt, the compound prefers p-type because the C-on-A antisite [such as Ge$_{\mathrm{Ta}}^{\mathrm{(1-)}}$] is a shallow acceptor producing holes yet the hole-killer donor of B-interstitial is unfavorable. (4) When B$=$Ni or Co, the compound favors n-type due to the dominance of B-interstitial defects (e.g. TiCoSb). We will show the calculated leading defect types and the dependence of carrier concentrations on chemical conditions for newly predicted half-Heulser insulators. This study is supported by DOE, Office of Science, Basic Energy Science, MSE division grant to CU Boulder. [Preview Abstract] |
Monday, March 2, 2015 10:12AM - 10:24AM |
A16.00010: Trends of semiconductivity in 3d oxides Stephan Lany Open shell transition metal oxides are usually described as Mott insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a Mott gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g., for energy applications. This presentation gives an overview for the band-structure trends of 3d oxides with special attention on the hybridization between the 3d crystal field symmetries with the sp bands, and on how this interactions affect the effective masses and the likelihood of self-trapping of electrons or holes. [Preview Abstract] |
Monday, March 2, 2015 10:24AM - 10:36AM |
A16.00011: Discovery of earth abundant light absorbers for solar water splitting: Mn$_{2}$V$_{2}$O$_{7}$ and beyond Qimin Yan, Pawl F. Newhouse, Guo Li, Jie Yu, Wei Chen, Kristin Persson, John Gregoire, Jeffrey Neaton Utilizing a first-principles data driven discovery approach with high-throughput computations and machine learning techniques, we screen for transition metal oxide (TMO) compounds with low band gaps and optimal band edges for solar water splitting applications. Combining the computational screening with the high-throughput experimental synthesis efforts, we identify the complex oxide $\beta$-Mn$_{2}$V$_{2}$O$_{7}$ as exhibiting a band gap and band edges that are near optimal for photocatalytic water splitting. Experiments, corroborated by theory, indicate that $\beta$-Mn$_{2}$V$_{2}$O$_{7}$ has a near-direct band gap near 1.8 eV. Our calculations further reveal a valence band maximum composed of mixed O-p/Mn-d states, and a conduction band maximum of V d-character, leading to dipole-allowed direct transitions at the band edges. Photoelectrochemical measurements indicate appreciable photocurrent from Mn$_{2}$V$_{2}$O$_{7}$ samples, corroborating our predictions. We further discuss design principles for guiding the discovery of more promising metal oxides with optimal band energetics for solar fuels applications. [Preview Abstract] |
Monday, March 2, 2015 10:36AM - 10:48AM |
A16.00012: Theoretical prediction of stable tin oxides: stoichiometry, electronic structure and possible applications Junjie Wang, Naoto Umezawa We have carried out a computational materials search for stable crystal phases of tin oxides in different composition ratios under ambient pressure condition. By employing density-functional theory calculations combined with evolutionary algorithm, we have identified several thermodynamically stable phases of tin oxides and investigated their dynamical stabilities by computing phonon vibration frequencies. We revealed the mechanism of determining the electronic structures of tin oxide crystals/van der Waals heterostructures through a systematic computational study of chemical bonding, band structure and Bader charges. Based on our theoretical analysis, we demonstrated that the predicted structures can lead to a desirable band structure for photocatalytic hydrogen evolution from water solution. Therefore, the tin oxides proposed in the present work have great potential as an abundant, cheap and environmentally-benign solar-energy conversion catalyst. [Preview Abstract] |
Monday, March 2, 2015 10:48AM - 11:00AM |
A16.00013: Pentahexoctite: A New Two-dimensional Allotrope of Carbon Aaditya Manjanath, Babu Ram Sharma, Abhishek K. Singh Structures with carbon atoms can be arranged in various shapes (polygons) that exhibit unique properties. This has spawned search in exploring such newer allotropes across dimensions. Although research has been extensive in bulk graphitic structures, there are several 2D allotropes that are yet to be unearthed. Here, we report a new allotrope consisting of 5-6-8 rings of carbon atoms, named as ``pentahexoctite.'' This $sp^2$ hybridized 2D allotrope has mechanical strength comparable to graphene. Electronically, the sheet is metallic with direction-dependent flat and dispersive bands at the Fermi level. It serves as a precursor for a stable 1D nanotubes with chirality-dependent electronic and mechanical properties. With these unique properties, the pentahexoctite sheet is another exciting addition to the family of robust novel 2D allotropes of carbon. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700