aspuru-list March 2016

aspuru-list@lists.fas.harvard.edu

23 participants
63 discussions

by Marlon Cummings

Hi: I have paper for each sub-group printer. I'll need a couple member from each office to stop by mine and grab a couple boxes. Thanks, MC -------------- *Marlon G. CummingsLab Manager, Aspuru-Guzik GroupMallinckrodt M136Department of Chemistry and Chemical BiologyHarvard University12 Oxford StreetCambridge, MA 02138617-496-9964617-496-9411 (fax)http://aspuru.chem.harvard.edu/ <http://aspuru.chem.harvard.edu/>*

8 years, 1 month

[Aspuru-Guzik Group List] Group Meeting, Mar 10, 2:30 PM, Div Room

by Ian Kivlichan

Hi all, Tomorrow Steven will give group meeting. See below for the title and abstract. Best, Ian ------------------------------------- Speaker: Steven A. Lopez Title: In Silico high-throughput screening of non-fullerene acceptor materials for organic photovoltaic devices Abstract: Organic Photovoltaics (OPVs) have shown a steady growth in efficiencies since the 1980s, and reported percent conversion efficiencies (PCEs) up to 12% are reported in multi-junction cells. OPVs are lightweight, easy to produce, and feature chemically diverse components. While PCBM is the standard fullerene n-type (acceptor) material, it is not without limitations, which include limited spectral breadth, small range of LUMO energies, and relatively high costs of industrial production. We have undertaken an in silico high-throughput screening utilizing the Harvard Clean Energy Project to explore the chemical space associated with non-fullerene acceptor materials. I will present an overview of the Clean Energy Project and some target molecules identified from a recent screening project. The initial screening library contains 100,000 perylenediimide, benzothiazole, diketopyropyrrole, and fluoroanthene-fused imide derivatives.

8 years, 1 month

[Aspuru-Guzik Group List] [qip] Friday the 11th

by Edward Farhi

Hi Quanta We will meet on Friday of this week at 11:00 in 6-310 as usual. Seth is going to tell us some stuff. See you there. Eddie *********************************************** Edward Farhi Cecil and Ida Green Professor of Physics Director Center for Theoretical Physics Massachusetts Institute of Technology 6-300 Cambridge MA 02139 617 253 4871 *********************************************** _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

8 years, 1 month

[Aspuru-Guzik Group List] TODAY - ITAMP/HQOC Joint Quantum Sciences Seminar: Herwig Ott

by Ploucha, Clare Dolores

HQOC/ITAMP Joint Quantum Sciences Seminar Wednesday, March 9, 2016 4:00 PM, Jefferson 250 Prof. Herwig Ott "Butterfly Molecules in a Bose-Einstein Condensate" This talk will give an overview of recent experiments in my group studying Rydberg excitations and their dynamics in ultra cold quantum gases. We use ionization processes of Rydberg atoms and molecules as a continuous probe of the system. For very small atomic samples with dimensions of a few micrometers, we reach the superatom limit, where only one excitation fits into the sample at the same time. For increasing size, driving strength and for finite detuning we observe the transition to a multiple excitation regime, where small clusters and correlated dynamics appear. For large Bose-Einstein condensates these clusters contain several hundred excitations and lead strongly correlated ion bursts emitted from the system. The discovery of Rydberg molecules offers another route to study degenerate quantum gases. Taking advantage of a single-photon excitation scheme to molecular Rydberg states, we can continuously measure the number of produced molecules. This has allowed us to probe in real time the double occupancy during a sweep over the superfluid to Mott insulator transition. Butterfly molecules are a special type of Rydberg molecules with exceptional properties. Using a single photon excitation to a Rydberg p-state, we observe for the first time these molecules. Due to their large dipole moment in combination with a small bond length, we resolve the rotational and pendular structure in an electric field. This opens new possibilities to study Rydberg molecules with long-range interactions in optical lattices. Dr. Richard Schmidt "A mesoscopic Rydberg impurity in an atomic quantum gas" Impurity problems have been at the forefront of research in condensed matter physics for several decades. In this talk, we show that Rydberg impurity excitations in ultracold quantum gases present a new frontier in impurity research. Here vastly different energy scales compete, signified in deeply bound Rydberg molecules of mesoscopic size. This situation poses a new challenge for theoretical physics and necessitates the confluence of methods ranging from mesoscopic to atomic physics. In our work, we develop a novel many-body theory for the non-equilibrium dynamics of giant impurity excitations Bose gases. Such single Rydberg impurity excitations have recently been observed, and we demonstrate that these observations can be understood from our theoretical approach which incorporates atomic and many-body theory. The crossover from few-body dynamics to quantum many-body collective behavior - manifest in the appearance of a novel superpolaronic state - is elucidated in an unified functional determinant approach, valid at zero and finite temperature. The time-dependent formalism is not restricted to Rydberg systems but can be generally applied to impurities in bosonic and fermionic environments and opens new possibilities to study impurity dynamics in mesoscopic systems. Reference [1] R. Schmidt, H. R. Sadeghpour, and E. Demler, arXiv:1510.09183 (2015). Student Presentation from 4:00-4:10 PM Refreshments Served from 4:00-4:30 PM Guest Presentation from 4:30-6:00 PM -- Clare Ploucha Faculty Assistant to Professors Lukin & Greiner and their labs Department of Physics 17 Oxford St., Lyman 324A Cambridge, MA 02138 P. (617) 496-2544

8 years, 1 month

[Aspuru-Guzik Group List] Excitonics/Perovskite Seminar: TODAY Mar 9, 4:30 pm, 36-462

by Catherine M Bourgeois

Center for Excitonics Seminar Series: Perovskite Seminar Reversible and irreversible ion migration processes in lead halide perovskites for photovoltaics March 9, 2016 at 4:30 PM/36-462 Eric Hoke Stanford University, Draper Laboratory [hoke-eric] Lead hybrid perovskites are a promising family of photovoltaic absorber materials that have achieved power conversion efficiencies of over 20%. Lead halide perovskites are ionic materials with a low lattice energy which are unusual properties for a photovoltaic material. It has been conjectured that this ionic character may be responsible for the material's defect-tolerant optoelectronic properties that have enabled its success as an efficient photovoltaic material. However, lead halide perovskites are highly susceptible to ion migratory processes which pose a significant challenge to the commercialization of stable devices. In this talk, I will present experimental evidence for a variety of ionic migration processes in perovskite thin films resulting from optical or electrical excitation. We observe from in-situ XRD measurements that bromine-rich (0.2<x<1) CH3NH3Pb(BrxI1-x)3 and other mixed-halide perovskites undergo a structural transformation under photoexcitation, segregating into two distinct perovskite phases over the course of minutes. The optical properties are also changed by this transformation resulting in the appearance of intense photoluminescence and absorption features from a lower bandgap phase. The perovskite surprisingly reverts back to its original structure and starting optical spectra when left in the dark. We suggest that photoexcitation induces halide segregation, resulting in iodide-rich domains. These lower bandgap domains act as traps and are likely responsible for the poor open circuit voltages generated by large bandgap, bromine-rich (0.2<x<1) CH3NH3Pb(BrxI1-x)3 solar cells. Perovskite solar cells frequently exhibit hysteretic behavior, which is greatly aggravated by the presence of moisture. The influence of electric field and moisture on perovskite films was investigated using a combination of photocurrent, optical, Raman, and Auger mapping techniques on lateral thin-film devices. These studies suggest that irreversible field-induced degradation in air occurs via a hydrated phase, in which the organic cation is loosely bound and can drift in response to an electric field, finally degrading the material to PbI2. Eric Hoke was recently the Associate Director of the Center of Advanced Molecular Photovoltaics at Stanford University. He completed his PhD from Stanford University in 2012 as a Fannie & John Hertz fellow and National Science Foundation Graduate Research fellow where he studied light harvesting mechanisms and degradation processes in organic photovoltaics and dye sensitized solar cells. Dr. Hoke recently joined Draper Laboratory as a member of Senior Technical Staff where he is developing imaging systems. This talk is part of the Perovskites Seminar Series organized by Sam Stranks and sponsored by the Center for Excitonics. For more info contact Sam: stranks(a)mit.edu<mailto:stranks@mit.edu> Light refreshments will be served. The Center For Excitonics Is An Energy Frontier Research Center Funded By The U.S. Department Of Energy, Office Of Science And Office Of Basic Energy Sciences

8 years, 1 month

[Aspuru-Guzik Group List] Special Seminar - Wednesday March 9, 2016 @ 11am

by Ploucha, Clare Dolores

Special Seminar Takasumi Tanabe Associate Professor at Keio University, Japan Optical nonlinear control at a very low power in ultrahigh-Q microcavity systems Wednesday, March 9, 2016 @ 11:00 am Cruft 309 *Light refreshments will be served* Ultrahigh-Q microcavities are attracting attention because they enable strong interaction between light and matter. Among various microcavities, photonic crystal nanocavity and toroid microcavity exhibit the highest Q/V, where V is the mode volume of the cavity. In the first half of my talk, I will discuss on our recent work on CMOS compatible fabrication of high-Q photonic crystal nanocavity and a tapered-fiber assisted reconfigurable cavity system that have extremely high coupling efficiency. In the second half of my talk, I will share some of our recent results on the Kerr comb generation in a high-Q toroidal microcavity system. I will discuss how the CW/CCW mode coupling and opto-mechanical coupling will affets the stability of the generated combs. I also discuss on the interplay between the Raman scattering and four-wave mixing effect in such small cavity system made by SiO2 Biography: Takasumi Tanabe received his Ph.D. from Keio University, Japan in 2004, where he studied adaptive shaping of amplified femtosecond pulses. On 2004, he joined NTT Basic Research Laboratories, Japan, where he started research on two-dimentional photonic crystal nanocavity systems. On April 2010 he moved to Electronics and Electrical Engineering in Keio University where he is currently an associate professor. He received Scientific American 50 Award in 2007, and the Commendation for Science and Technology (The Young Scientists’ Prize) by the Minister of Education, Culture, Sports, Science and Technology, Japan, in 2010. Dr. Tanabe has published more than 50 papers (h-index: 25) and delivered a number of post-deadline talks and invited talks in conferences such as CLEO and SPIE Photonics West. He is currently serving as an Associate Editor for AIP Advances. Harvard John A. Paulson School of Engineering and Applied Sciences Pierce Hall, 29 Oxford Street Cambridge, MA 02138 P: 617.496.1460 | E: rstiles(a)seas.harvard.edu<mailto:rstiles@seas.harvard.edu>

8 years, 1 month

[Aspuru-Guzik Group List] Fwd: Gaussian software - Gaussview desktop software

by Marlon Cummings

Can I ask for one person to respond to Marcia? Thanks! --------------- *Marlon G. CummingsLab Manager, Aspuru-Guzik GroupMallinckrodt M136Department of Chemistry and Chemical BiologyHarvard University12 Oxford StreetCambridge, MA 02138617-496-9964617-496-9411 (fax)http://aspuru.chem.harvard.edu/ <http://aspuru.chem.harvard.edu/>* ---------- Forwarded message ---------- From: Chapin, Marcia L. <chapin(a)chemistry.harvard.edu> Date: Tue, Mar 8, 2016 at 2:03 PM Subject: Gaussian software - Gaussview desktop software To: "Cummings, Marlon G" <marloncummings(a)chemistry.harvard.edu> Hi Marlon, I have a question about who uses and knows about the Gaussview Software used in conjunction with Gaussian software on the Odyssey cluster. The CCB Library at one time had a disks with Gaussview v.5.09 software for MAC and PC. We no longer have these disks and Research Computing has no record of a license for the Gaussview product. Does anyone in your group know who had the license for the software? If this product is needed in the future, folks will need to contact research computing to get a site license. Please let me know if anyone knows the status of Gaussview. Thanks! Best, Marcia Marcia L. Chapin Librarian Harvard Chemistry & Chemical Biology Library 12 Oxford. St. Cambridge, MA 02138 ***************************************** voice: 617-496-2728 fax : 617-495-0788 chapin(a)chemistry.harvard.edu

8 years, 1 month

[Aspuru-Guzik Group List] Tomorrow - Prof. Nandini Ananth presentation THEOCHEM

by Stéphanie Valleau

*Path Integral Methods for Simulating Nonadiabatic Charge and Energy Transfer Dynamics* *when*: 03/09/16 4:00pm *where*: MIT Building 4, Room 163 *Prof. Nandini Ananth (Cornell University)* Simulating inherently quantum mechanical charge and energy transfer processes in the condensed phase remains an outstanding challenge to theory. The high computational costs associated with exact quantum dynamic simulations of large systems necessitate the development of approximate methods that (i) exhibit low computational cost and near-linear scaling with system dimensionality; (ii) capture important quantum effects including tunneling, zero-point energy, and coherence effects; and (iii) employ a consistent framework to describe transitions between electronic states and the dynamics of nuclei to accurately capture nonadiabatic processes. In this talk, we will discuss several well-established, approximate methods derived from the real- time and imaginary-time path integral formulations of quantum mechanics. We will explore their regimes of applicability based on the criteria outlined above. We then introduce a novel method developed by our group for the direct dynamic simulation of photo-induced chemical reactions in the condensed phase, Mapping-Variable Ring Polymer Molecular Dynamics (MV-RPMD). Finally, we will numerically demonstrate the accuracy and applicability of this method in simulations of photo-induced excited electronic state dynamics.

8 years, 1 month

Re: [Aspuru-Guzik Group List] clicker

by Semion Saikin

Got one from Borja. Do not need more. Thanks!

8 years, 1 month

[Aspuru-Guzik Group List] looking for a clicker

by Semion Saikin

Hi Guys, Does anybody have clicker for a presentation? Can I borrow it for tomorrow? Semion

8 years, 1 month

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aspuru-list March 2016