Outline Motivation & Goals What is a Zeolite How Many Space Groups are There The Search Procedure

Outline Motivation & Goals What is a Zeolite How Many Space Groups are There The Search Procedure www.phwiki.com

Outline Motivation & Goals What is a Zeolite How Many Space Groups are There The Search Procedure

Cannon, Dawn, Managing Editor has reference to this Academic Journal, PHwiki organized this Journal A Database of New Zeolite-Like Materials Michael W. Deem Rice University TexPoint fonts used in EMF: AAAAAAAAAAAA Outline Motivation Monte Carlo sampling to construct database History of database of hypotheticals Geometric, topological, in addition to physical properties of the predicted materials Challenges M. W. Deem, R. Pophale, P. A. Cheeseman, in addition to D. J. Earl, J. Phys. Chem. C 113 (2009) 21353-21360. R. Pophale, P. A. Cheeseman, in addition to M. W. Deem, Phys. Chem. Chem. Phys. (2011) doi:10.1039/c0cp02255a. Motivation & Goals Create database of hypothetical zeolite (SiO2) structures Structures should have favorable framework energies Screen as long as materials with unique properties to identify interesting synthetic targets Catalysis, sorption, k Identify synthesis conditions (hard problem!) LTL EMT VFI

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What is a Zeolite SiO2 structure Four-connected network 3D periodic 190 known zeolites (Si1-xAlxO2) Used as long as Catalysis, especially petroleum refining Gas separation Ion exchange LTL EMT VFI How Many Space Groups are There http://cst-www.nrl.navy.mil/lattice/spcgrp/index.html The Search Procedure Loop through space groups Loop through 3 a,b,c 30Å, dr=3Å; , , , d=10° Loop through 12 20 T atoms/1000Å3, d = 2 Loop through 1 nunique 8; nunique 4.5 ntot / nsymm Run zefsaII 100 times (solves 86% of known structures) Keep structures with E < 0 Keep best example (lowest E/atom) of each unique topology Monte Carlo Procedure For a unit cell with a given space group symmetry, tetrahedral atom density in addition to number of crystallographically unique tetrahedral atoms we want to identify as many reasonable topologies as possible To do this we use (many) simulated annealing Monte Carlo simulations The Figure of Merit Contains geometric in addition to density terms Weighting parameters selected to efficiently solve known zeolite topologies Note only tetrahedral atoms included (no oxygens) Euc Aside: Structure Solution SSZ-77 ZEFSA/ZEFSAII originally developed ( in addition to still used) as long as zeolite structure solution One can also include a match to X-ray powder data in the figure of merit to directly solve structures This approach has been effective in solving the structures of at least a dozen zeolites in addition to other layered structures to date SSZ-77: New high-silica zeolite Structure solution elucidated synthesis conditions Template decomposed Decomposition product was the SDA Hypotheticals Database Create database of hypothetical structures Thermodynamically accessible Mine as long as structures with unique properties Identify synthesis conditions to make LTL EMT VFI History of Database Roughly 2000 structures in 1992 JACS 114 (1992) 7189-7198 Compared to a few hundred in Joe V. Smith database Produced from unit cells of known structures Reproduced in 2003 J. Phys. Chem. B 107 (2003) 8612-8620 New search begun in 2004 Geometrical in addition to topological features investigated Ind. Eng. Chem. Res. 45 (2006) 5449-5454 J. Phys. Chem. C 113 (2009) 21353-21360 Phys. Chem. Chem. Phys. (2011) doi:10.1039/c0cp02255a Zefsa: http://www.mwdeem.rice.edu/zefsaII Using the NSF TeraGrid Method is perfect as long as scavenging idle CPU time For a typical desktop processor, 1 simulated annealing run takes on the order of minutes Condor is an efficient implementation of CPU scavenging at Purdue University Over the last 5 years we have scavenged approx. 6 million CPU hours from machines on the NSF TeraGrid NSF TeraGrid Usage 6th biggest user of TeraGrid in 2006 Largest user at Purdue in 2006 Throughput possibilities – Linux circa 2008/11. Note peaks in addition to valleys Other Hypothetical Databases See www.hypotheticalzeolites.net (an excellent website) Hosts the Foster/Treacy database Provides links to our database, Bell/Klinowski hypotheticals, Predicted Crystallographically Open Database, Reticular Chemistry Structure Resource, Euclidean Patterns in Non-Euclidean Tilings, Jilin University Forster/Treacy Database We are very grateful to Martin Forster in addition to Michael Treacy as long as hosting our database on www.hypotheticalzeolites.net Forster/Treacy Database 933K GULP refined structures (silver) 333 gold structures Statistics About 3x duplicates in silver database Of non-duplicates, about 5% within +0.1 eV/Si on BGB as long as cefield ( +60 kJ/Si Jackson/Catlow as long as cefield) About 30% of these are within +30 kJ/Si of quartz Thus, about 5,700 structures in silver database within +30 kJ/Si Earl/Deem database 4.4M unique structures 2.6M refined with GULP 1.4M within +60 kJ on SLC interatomic potential 330K within +30 kJ on SLC interatomic potential Search Capability Plan Organize in addition to analyze database Density Pore size Ring distribution Coordination sequence PXD (Le Bail’s PCOD in addition to P2D2) icdd, icsd, MDI-JADE, CrystalMatch commercial databases Viewing the Database www.hypotheticalzeolites.net/DATABASE/DEEM/ Si-Only Results 4.37 million structures found As the structures produced by our Monte Carlo annealing procedure are energetically favorable, many have good framework energies Coverage of Hypotheticals 86% of known structures solved Add O atoms between all T atoms that are connected (recall that only T atoms are included in initial sweep of crystallographic space) Use an atomistic as long as ce-field (Jackson & Catlow, 1988) in addition to energy minimize the structure using a Newton-Raphson procedure in the GULP program Energetic Refinement Procedure Add O Energy minimize Refined Results Roughly 4 370 000 structures 3.3M unique Si-only structures 2.6M unique SiO2 structures Two interatomic potentials used Polarizable SLC Non-polarizable BKS Thermodynamically accessibility SLC: 330k structures within +30 kJ/mol Si BKS: 590k structures within +65 kJ/mol Si Interatomic Potential Anomaly SLC in addition to BKS as long as ce fields contain an anomaly: u=ae-br –c/r6 Overlapping atoms or cores in addition to shells can have negative, infinite energy This will result in structures with poor geometry, but overlapping atoms, to appear to have favorable energies E.g. structures with energy below -quartz. This anomaly was fixed by changing the exp-6 potential to extrapolate to a large value at r=0 Largely eliminates “too good” structures with energies below -quartz. Some Structures From SLC database Structures with energies no greater than 30 kJ/mol Si of -quartz Typical, zeolite-like structures Framework Energies of Quartz in addition to Known Zeolites Most known zeolites are within 30 kJ / mol Si of the framework energy of quartz in the SLC interatomic potential Of the 4.37 million topologies from the initial search, 330 000 SLC topologies have been found in this range (or better); 590 000 in BKS subset From Foster et al., Nature Materials 3 (2004) 234 Cannon, Dawn Southern Accents Managing Editor www.phwiki.com

Energy-Density Distributions Two major clusters of zeolite-like materials One group around 18 Si / 1000 A3 One group around 8 Si / 1000 A3 SLC BKS Energy-Density Distributions SLC in addition to BKS structures have similar distributions The group around 8 Si / 1000 A3 is novel Corma has made structures in this range: PNAS 107 (2010) 13997; Nature 458 (2009) 1154. SLC BKS Zeolite Synthesis Mechanism Lie at low-density edge of zeolite-like distribution Probably due to current synthetic techniques Mechanistic explanation of feasability factor D. Majda et al. J. Phys. Chem. C 112 (2008) 1040-1047 Can the rest of the distribution be made Can the low-density structures (8 Si / 1000 A3) be made SLC BKS

Ring Distributions Fundamental, non-decomposible rings SLC in addition to BKS topologies are similar Quite a few large-membered rings Distribution not sensitive to presence of 3-rings SLC BKS Ring: Hypotheticals vs Knowns Reasonably good agreement between predicted in addition to known ring distributions SLC in addition to BKS ring distributions are similar More large-membered rings predicted to exist 3-rings correlated with 9-rings in knowns, but not in hypotheticals SLC BKS Knowns Low Energy Structures Structures with energy below quartz Can be artifacts of overlapping shells or atoms in SLC or BKS In this version of the database there are only 2 within -30kJ/molSi as long as SLC in addition to none within -65kJ/molSi as long as BKS

Big Picture Questions/Challenges Can we identify structures as long as particular applications e.g. CO2 separation How does one synthesize them Which structures can be synthesized What OSDAs can be used to make them Also: solution conditions, co-templates Significant reason as long as promise

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