Automated design of thermally stable heteroleptic precursors by computational screening 

Session Notes:

PRESENTER

Dr. Simon Elliott

Director of Atomic Level Process Simulation  Schrödinger Inc.

LINKS

 


ABSTRACT

Ligand choice in ALD/CVD precursors is crucial for throughput, stoichiometry, impurities and process temperature. Heteroleptic precursors (containing more than one type of ligand) are one way to compromise between conflicting chemical requirements. However to date we have barely ‘scratched the surface’ of the vast chemical space of possible heteroleptic precursors. As an example to illustrate the magnitude of the design problem, 8,855 chemically-distinct complexes can be formed by combining four of 20 ligands around a tetravalent metal center. Clearly, an exhaustive experimental analysis is not possible. Instead we look to computational screening to narrow down the search to the most promising options. Here we present a computational approach for screening metal precursors with respect to thermal stability. The computational strategy is illustrated on the example of Zr precursors for zirconium nitride, used as a hard coating to protect industrial parts in corrosive environments. 
 
CVD precursors should decompose unimolecularly at elevated temperature in the reactor and we therefore seek complexes with moderately low energies for homolytic bond dissociation (i.e. into a pair of radical fragments). ALD on the other hand requires the gas-phase stability of precursors to be as high as possible, as this dictates the upper temperature limit for ALD. 
 
We first enumerate over ligands. Even a small ligand library of just six O-free, N-bearing ligands (amines, amidinatescyano and guanidinate, with various alkyl groups) gives 6^4=1296 possible complexes, but many are symmetrically equivalent or over-coordinated, leaving 81 for optimization with density functional theory (DFT). To study thermal stability requires a second phase of enumeration, over the 1280 different bonds that can be broken in these complexes, yielding a set of radical fragments that are also computed at the DFT level. It is clear that every step in this computational workflow requires robust and efficient automation. 
 
DFT reveals that the lowest bond dissociation energies are obtained for cleaving intact ligands from the metal. The least thermally stable complexes are found to be zirconium amides with bidentate amidinates/guanidinates, and so we predict that these would be the best CVD precursors. We observe very little steric effect when replacing methyl groups with ethyl groups. By contrast, cyano groups have a stabilizing influence, suggesting that similar electron-withdrawing groups would be useful as spectator ligands in heteroleptic precursors for ALD. On the basis of this sample system, we discuss the general requirements for chemical enumeration software and the limits faced by automation.

0:00:01   Hello. My name is Simon Elliott from Schrödinger computational chemistry companies specializing in
0:00:07   atomic level process simulations. Thank you for coming to my talk at the particle Vale de event. I
0:00:13   thank you to forge Nano putting on this event like Teoh. Start my presentation. I'll be speaking
0:00:21   about the computer design of thermally stable precursors for L D and C V. I told my co authors in
0:00:29   Schrödinger who helped with this study
0:00:34   what we're doing in a computational screenings, the same as other screening approaches where
0:00:40   surveying a wide volume wide area of chemical space and we'd like to find that one nuggets those few
0:00:47   exciting new precursors that fulfill the property. So we're looking for So this is quite a difficult
0:00:55   feast. In the case of chemical screening, uh, the space is very large. When we're looking at organa
0:01:03   metallic precursors. It's all about choosing the Liggins. And here is a selection of some of the big
0:01:08   guns that are frequently used in the area of A, L, D and C V. And combining all these Liggins I can
0:01:15   lead to very, very many precursor compounds. So we want to use computers to help select the best
0:01:21   precursor compounds screen and provide the best candidates for an experiment study. In this study,
0:01:31   we want to look at hetero elliptic precursors. Hydroelectric means were combining different Liggins
0:01:36   in one molecule. So shown on the left is a home electric precursor of zirconia. The SL vessel, a
0:01:44   might on shown of the rice, is a naturalistic precursor that combines CP Rail on three messily
0:01:53   rights on the set. Reelected Precursor, called Zuelle, is in use in high volume manufacturing
0:02:01   because it combines some of the advantages of the two different vacants stability of the CPI rig on
0:02:07   the re activists in the A my groups. So this is a profitable strategy and but one of the problems is
0:02:16   is a very large space of ways that you can combine different Liggins together into one molecule. And
0:02:22   that's what we're going to address in this job. So how many possibilities are there? The formula is
0:02:28   given there on the left. If you have a complex which is cute, Negan's on you have a library of
0:02:35   Liggins, maybe, and Liggins in your library. The show on the X axis. This formula gives you the
0:02:40   number of possible complexes that you should consider, For example, if we look us Tetra Vaillant
0:02:47   complexes like Cicconi, um, the topic of this talk. And for example, if you have 11 different
0:02:53   ligaments, you can combine them together in 1000 and one different weights around. There's a cobia
0:02:59   center. So this is a large problem, a large number of structures of large number monikers to be
0:03:07   considered. And clearly you couldn't synthesize all 1000 molecules testing experiment Ah, on the
0:03:14   computer, running this many molecules is very, very doable. Such calculations typically take about
0:03:21   one hour per complex, so that would be 40 CPU dates on a typical computer. And if you run in
0:03:29   parallel, you could get through those many calculations a few days. So computational screening it is
0:03:39   much, much faster than its experimental partner, and it could therefore be used to narrow down the
0:03:47   space just a small number of molecules that can be looked at in more detail. So in this study were
0:03:53   actually going to just look at the combination of six different ligaments. Now, the shoulder on the
0:03:58   left plugging an equal six into this formula, gives US 126 unit complexes on of them were going only
0:04:05   going to look at the ones that are up to six coordinates. So that's 81 different molecules that are
0:04:10   six courts. So let's look at the Ligand Library. We have three mono dentists. Liggins on three by
0:04:16   dentist Liggett's Oman. Identical twins attached fire one after by dentition touch fire to Assam's
0:04:22   two teeth to the metal center. The big guns are all nitrogen bearing and oxygen free, so I selected
0:04:30   two. Primary A minds dimethyl a mind and I f l A M I. Just so they differ in the length of the Al
0:04:36   Qaeda group the Scion No ligament and then three by Dent eight Liggins to originates, one with two
0:04:44   methyl groups. The other was to Ethel. Groups swing in their differing in the size of the Al Qaeda
0:04:48   substitute int on ago annotate that has an extra nitrogen added to the backup. So, as I say, putting
0:04:57   together these six different Legans, all the different possible had to adapt precursors. We get 81
0:05:02   different complexes as an oxygen free ligand. It's interesting to see what kind of oxygen free
0:05:09   compounds this ligand sesh could be used for. Of course, mostly the A, L, D and CVD literature and
0:05:16   Cicconi, um is dominated by zirconium oxide and this very, very many studies of that process for
0:05:23   zirconium nitrite we find a lot less relatively simple. Uh, precursors have been used in each case
0:05:31   the whole dialectic eletricas. Any mines, you know, the thermal or plasma guilty. There's also a
0:05:37   published study on the CBD of zirconium carbide. Just using a single source contain CP Rick on day
0:05:43   mites. So plenty of space for innovation here. Let's see what kind of costs full compounds could
0:05:50   fulfill what's needed. Frailty. So our strategy is start with the metal center to find our ligand
0:05:57   library that have introduced to you and then that the computer systematically generated all the
0:06:01   possible structures. That's cause of liberation. We have our 81 different complexes and then submit
0:06:08   that to quantum mechanics for optimizing the structure. Andi, for computing a property, so we need a
0:06:14   proper C by which to decide which are the best molecules of which other less good molecules. So this
0:06:20   isn't metric or screening criteria. And again, quantum mechanics, or indeed, molecular mechanics can
0:06:27   be used to compute these properties, and hence screen out the best molecules. What we need here is a
0:06:34   robust workflow, right across the whole strategy, so this we can reliably run hundreds and hundreds
0:06:40   of calculations that was happening crashing, and that's really where the skin of this kind of thing.
0:06:49   So what kind of properties might be we'd be interested in for a precursor? These are the main things.
0:06:55   The synthesis should be cost effective. The precursor itself should form a the Quirt, ideally at
0:07:02   room temperature and should be volatile. Three. A port. It should be thoroughly stable for a lady
0:07:09   reaching the surface of the substrates without decomposing. And in CBD, on the other hand, we'd like
0:07:15   it to decompose of the temperature when it's heated in the gas phase of produce active species that
0:07:19   react with surface about, obviously at the surface. In both cases, we want the target material to
0:07:27   grow and not an impure material and not a material that is contaminated by byproducts. So some of
0:07:35   these properties can be computed easily, and some our little more chicken listed there. Some of the
0:07:42   factors that we have to consider for now, let's just focus on the main property that we're going to
0:07:47   consider in this talk, which is durable stability. And for that we're going to use the bond
0:07:52   dissociation energies of the molecule as a way to estimate the terrible stability.
0:07:59   So thestreet she here is that when the molecules the organa metallic precursors air in the gas phase,
0:08:06   they can be dissociated perfectly by the home electric cleavage off their constituents Bonds that
0:08:13   this is that a problem in a l D. But is perhaps what is desired at CPD. So we compute the energy
0:08:22   required to cleave all the bonds in a molecule. And we re cleave the bonds when politically, as I
0:08:30   say so this generates radicals. And these are what needs to be computed to get the bond dissociation.
0:08:36   So this is actually another level of in your operation and our problem. We have 81 complexes of
0:08:41   those complexes contained over 1200 bonds. So I listed there the numbers hundreds of hundreds of
0:08:47   carbon carbon bonds, carbon nitrogen bonds, carbon hydrogen on the metal ligand bonds themselves,
0:08:53   zirconium, attrition, bonds that actually are the center of the complex. So this would also be a
0:08:59   very tedious set of calculations to set up by hand, many many of the fragments are actually the same.
0:09:05   And so you could do the job more efficiently on. We have to compute to do that as well. So the
0:09:10   computer works through all the possible structures and fragments on puts together the energies that
0:09:15   we need. So here are the details, the calculation and it's done density functional theory to be
0:09:21   three out by p. Functional good basis session Aren't Spitko organization So here is a molecule to
0:09:29   illustrate to you what we mean by the bond dissociation. This complex is how to roll Epic it is too
0:09:37   uh, dime Ethel A might begins d m a r and any to and it has to die s away. My Lincoln's see the one
0:09:47   that the charges like ethylene has to effort groups attached to the night And all four Liggins are
0:09:53   bonded to the central zirconia. So coney amassing which is in pale blue. So the different bonds in
0:10:00   this molecule could be dissociated. I plus the bond dissociation at the y axis the to the yellow and
0:10:12   orange discs show the energy required to break the vessel to a right barked method. Nitrogen look
0:10:20   zirconium on the day, so we find 272 to 54 cabbages. But bowl and that's what's closet here. Another
0:10:29   bonds that come broken is the nitrogen carbon bond, and these data are shown US crosses and diamonds.
0:10:35   And you see the cross is shown here for this particular molecule. The carbon carbon bonds could be
0:10:41   broken to yield at methyl radical on. This is also shown with across 3 29 Villagers Brummel. The
0:10:49   carbon hydrogen bonds could be broken. They were very, very many hydrogen atoms in this molecule,
0:10:53   but actually most of them are symmetrically identical since in the end, just three different bond
0:10:57   energies ranging from 372 300 to 450 carriages promote. On these air shown is green crosses. Finally,
0:11:06   there's a mode of dissociation called pizza hydrogen elimination. But the beater hydrogen from one
0:11:11   of the ethnic groups can transfer to the nitrogen but former stable, close shelled species again, in
0:11:16   this case, which means this is often quite a low energy decomposition pathway, especially for a
0:11:22   mites, and the resulting byproduct is the thing. So for this molecule, we can see this one as an
0:11:29   energy difference of just 205 Villagers probable making us the most favorable off the bond
0:11:35   dissociation reactions in this particular article. So a prediction for this molecule will be that is
0:11:40   decomposes. First of all by this beast or hydrogen elimination passed away. And so that was just for
0:11:48   one molecule. Now I allowed in the data for the other 81 molecules. This fills up the graph, but
0:11:56   I've done here is just sort it the molecules from 1 to 81 by their lowest bonds association. So the
0:12:03   ones on the left inside How fee? Uh, their minimum bond association energy is high on for the ones
0:12:10   on the right. Inside their minimum bond dissociation energies, lows there more easily decomposed. So
0:12:17   that no stable ones on the left, most on the stable ones and right inside. And the numbers 1 to 81
0:12:22   or a simple rank ordering a lot of data. It's maybe a bit hard to take in so I can show different
0:12:32   parts of the data to help you understand this. These are just the missile ligament bond dissociation,
0:12:39   energies. So just from the zirconium to the nitrogen on, you can see a huge range, even though it's
0:12:44   always a zirconium nitrogen bond. The energy required to break its ranges from best in 150 kept just
0:12:52   normal. Up to over 450 captures befall three times stronger. We can see some Trans The Scion Oh
0:12:59   Bonds, the metal scion of arms tailed blue, is always the most stable, and that's expected for
0:13:06   Sacconi. The vessel to a mite on identity. A might is generally the least stable within this class
0:13:17   of compounds. You see, there's a range over maybe 100 colleges provoked depending on which complex
0:13:23   we're looking us. We can see this, whether it's methylene night or Ethel A might really doesn't make
0:13:30   a great deal of difference. One could maybe say that more of the dinette Soleil minds are more
0:13:35   stable and more of the diocese reminds our best stable. Basically, the to Diggins behaves the same
0:13:42   of the are a group doesn't have a huge difference in between. We see the energies for the by
0:13:47   dentists figure. This is a shown in dark blue green grey, and these are much higher. So it is
0:13:53   already an indication that the by dentists Legans are bound more strong. I suppose consistent with
0:13:58   the fact that they have two bombs. Looks, you know only when you compute these energies do you find
0:14:05   the way it's Quantum mechanics works, so those are the metal ligand bonds, and each complex has up
0:14:12   to four of these measures licking the bonds and therefore up to four dots shown on this graph. Here,
0:14:18   then, are the remaining days of these roll the carbon, carbon, carbon, nitrogen, carbon, hydrogen on
0:14:25   the beach, hydrogen elimination squares and actually the beater. Hydrogen and elimination is often
0:14:31   the lowest of the bond association entries, but not always. It's not always the way this is kind of
0:14:37   a might based molecules will decompose the carbon hydrogen bonds. The green crosses are generally
0:14:44   the most. That's stable bonds, and
0:14:48   so now essentially, these data can be used to the first level of screening the ones on the left hand
0:14:55   side of the ones with the highest energy required to make some decompose. These are the most
0:15:00   thermally stable on we would suggest. These are the candidates molecules for Atomic Claire
0:15:05   deposition. On the right hand side, these molecules decompose much more readily, and in fact you can
0:15:13   see we can predict the way they're decomposing in a Well, yeah. Uh, well separated fashion. It's the
0:15:21   A might or the Beecher hydrogen elimination that will be the decomposition pathway. So these might
0:15:26   be candidates for CVD, where we understand the decomposition through these calculations. So let's
0:15:33   look in more detail at the best. The top 10 or top 20 Reality, um, just stand there is a blow up of
0:15:43   the 20 most stable here again, it's just their metal ligand bond breaking, so you can actually see
0:15:50   which Diggins Air involved in each of them on have also out of here the label of each molecule this
0:15:58   piss cumbersome and confusing to look at. So we'll go through them molecule by molecule and identify
0:16:03   some trends. But even without looking at the chemistry, we could just pass this list to the
0:16:09   experimental colleagues on, say, choose some of these molecules. They should be, sir, very stable.
0:16:14   We've done our screen. Or we could go on and do a second level of screening on Look at some of the
0:16:19   other properties that you want to optimize in the night and l d precursor we look at that's towards
0:16:26   the end of the talk. But for now, let's see. Are there trends and is there chemistry that we can
0:16:31   understand from this data set on? The first thing about the highlights are and the difference
0:16:36   between the simple A mites such as DME dimethyl any on the fly on a group CIA on shown here circled
0:16:45   are the home electric chantry kiss molecules was get tricked a trick. It's saya No, on the Tetrick
0:16:51   is a might on the cyanide molecule is the most stable one we find the whole fest on this is expected
0:17:00   to the zirconium. Scion of armed is very strong, and it's unlikely that Sino relations molecules
0:17:09   would be used in a bloody because they aren't volatile. But we can include them in our computational.
0:17:14   That study, and so is to find out what kind of chemistry they, how they before the chemistry is like,
0:17:22   what effect? This kind of molecule hand. This kind of licking tiles on the molecule is a hole. So
0:17:27   looking here A. These days, sir, we can see that the A might normally has its upon dissociation
0:17:32   energy for the mistletoe. My bond of about 250 cabbages, Pro Bowl, but adding one the Scion Oh,
0:17:39   group is a spectator makes that bond makes that yellow dash go up. So makes us message way might
0:17:46   bond and nearly 50 colleges from all stronger on adding another siamo makes it stronger again. And I
0:17:53   think 1/3 sandal have makes this, Ah, even stronger, almost a strong as the zirconium SIA nobody. So
0:18:03   this is an effect Scion a group is having on the other Liggins here the same day suggested tabular
0:18:10   form. We're going from the electrical system. It's a mite on the left, the Tetrick. It's cyanide
0:18:14   content with rice, placing one leg with the other, and you can see this vessel to a might. Bond
0:18:19   strength is increasing across the road. What this means is that other bonds take over as the least
0:18:26   stable in the molecule. You see them shown here in bold. That's a in these middle compounds. It's
0:18:32   the nitrogen to metal bond that becomes the association actuated. His favorite, or even the carbon
0:18:39   hydrogen bonded this molecule. And so what we're seeing is that the scion no group has a spectator
0:18:45   ligand, unstable eyes, the zirconium nitrogen bonds of the other. And while it's Diana might not be
0:18:52   used. A nail d maybe other electron withdrawing groups will be interesting if this is the kind of
0:18:57   effect you'd like to have, making an otherwise unstable, partially molecule, much more state. And we
0:19:05   can also look at the by dentists. Liggett's If you remember, half of the Ligand library was by
0:19:09   dentist. And here we see one of the guanine Denyce complexes with three Sino groups on the dimethyl.
0:19:18   Imagine age three science groups on these come in as molecules Numbers three and four. So they're
0:19:23   some of the most thermally stable off the complexes. Study This shows us. And if you see the green
0:19:30   darts in the dark blue dots, they're actually the energies required to break those metal to ligand.
0:19:37   Advance to the identity Liggins. So these are very, very stable Legans more stable in fact, that the
0:19:43   scion of groups in these complexes uh and
0:19:49   this is a trend, as I said that we see right across the
0:19:54   study that the Biden taste any minds. Imagine eight square originates are more stable than the mono
0:20:00   devastating. Here's another three examples again from the very extreme left hand side, very stable
0:20:06   molecules on in this case, we've two of the by identity begins to Siam groups here. The structures,
0:20:13   those three molecules, they have very high bond dissociation energies for the message taken parts.
0:20:21   So we conclude that of identity. Liggins themselves bombs strongly to zirconium. Yeah, but what
0:20:27   other effects? They further down this list you can see now we're still in the top 20. But some of
0:20:33   these molecules are a bit less stable in terms of their vessel a might, bomb and strengths of the
0:20:39   yellow dots where the maybe the parents molecule with two a mites and to sounder groups as a kind of
0:20:46   an energy. Around 300 Villagers from all this is lowered to 50 when you add in one of identically
0:20:52   guns or even to buy identically on. This might be an indication of the crowding that the large by
0:20:57   identically gets calls because they pushed their way into the coordination sphere around. You're
0:21:02   some more examples. And these ones, I also have the by dented Liggins. I don't want her to of the so.
0:21:11   The conclusion here is that either by identity licking itself, is very strongly bound. It
0:21:15   destabilizes the neighboring on a dentist, so this would have to be taken into account of designing
0:21:21   one cook with identically. If we go to the other end of the set of complexes and going down close to
0:21:30   generate 81 of the least stable, we can have a look at what causes the molecules to be unstable and
0:21:36   again here by downtick Liggins are having a big effect. All of these complexes have to buy dented
0:21:43   Liggins and to modern technique. It's on. That is what is destabilizing. Well, no Jen, take chickens
0:21:49   so the orange yellow dots are pushed right down to nearly 150 chemicals.
0:21:57   And so we won't dig into the chemistry anymore. There's more. We can look at their in terms of the
0:22:02   carbon hydrogen, the peace are interesting elimination so on. But as I say, really, the screening is
0:22:09   don't we've classified the molecules according to this one property, and now there are other
0:22:13   properties that we really want to optimize for the A L D. Application. Let's look at those parties
0:22:22   again. If we were to try to him to produce molecules that could be synthesized, I think this is not
0:22:30   something that you can just compute with a single number but instead we'd probably take advice from
0:22:37   synthesis and build it into the way the enumeration is done. For examples we might constrain the
0:22:42   integration toe only have two different begins in. That's probably the best way to build in
0:22:48   synthetic requirements. Ah, liquids, uh, precursors, volatile precursors. This all comes back to
0:22:58   inter molecular forces, quantitative and computation off. The partial pressure, for example, is not
0:23:06   something that is straightforward. Do you did push his state of the art before we could do? But
0:23:12   there are quicker on qualitative ways to assess. But there's something is a liquid or whether it's
0:23:17   volatile based on the introduction of forces. We can't, of course, close the mass of a molecule. We
0:23:25   can calculate its entropy quite easily. It's polarize ability and because he's of energy of a liquid.
0:23:32   And so these are ways that we can attack those properties and we've looked at thermal stability, and
0:23:38   but what I'd like to just giver as another example of someone compute quite accurately and easily
0:23:44   onto mechanics is the reactivity off the A L D. Process itself in terms of thermodynamics, and here
0:23:51   again we can identify one number that encapsulates the reactivity in terms of actually making the
0:23:59   targets material. So here again, are the complexes. No, I've I've left out the scion. Oh, precursors
0:24:06   on the basis that they will never be useful. Eso from the 81. We've now gone down to 35 that have no
0:24:12   scion. Oh, in the there's all the data But that's just focus on the minimum bond association energy
0:24:18   of each of molecules. They are not showing on the left hand X axis and on the right and ex I'm sorry,
0:24:25   Why access the left by access now on the right hand, why access? I'm showing a single reaction
0:24:31   energy, which is a measure of how likely the molecule is to form zirconium nitrate product. So this
0:24:39   reaction energy includes the bond strength of Cicconi, um, to nitrogen, but also the the difference
0:24:47   in bonding and eliminating the Liggins with protons on. We want this reaction energy to be as low as
0:24:54   possible. So a negative number, if possible or small positive number. The higher the number, the
0:24:59   less likely it is to be a good l D process with no barrier. The proceeds a low temperature. So for a
0:25:05   low temperature, easy ale de process. We want a no number. So looking at that, the black dots reach
0:25:13   the precursors. We could see this. It's actually quite good news. Most of the low energy favorable
0:25:20   processes are on the left hand side, so they correlate with the thermally stable molecules. So let's
0:25:27   look at the actual identity of the ones that are the best. Thes five molecules are the most reactive,
0:25:34   and you can see that they're all involvement mono dentist mines ranging from the trickiest I assault
0:25:41   image on way to the Tetrick. It's like math Olumide on all the possibilities in between. So those
0:25:48   molecules, since there the left hand side of the graph that certainly stable. And since there on the
0:25:54   lower part of the graph
0:25:57   meconium nitrate process, there are also likely to be viable. No temperature, certain processes, and
0:26:04   the next few molecules we can see all have just one by dentist uh, ligament shown here and ground.
0:26:14   And then a mixture of the modern identically seal. The three eso these fall into a class of
0:26:19   molecules on. There seems to be a clear trends there that again, these molecules should undergo a
0:26:25   lady quite well, having more by dentist begins, pushes up this reaction energy and makes it less
0:26:31   favorite. So it's pretty good news and a the most thermally stable molecules are also the ones that
0:26:38   are most reactive in terms of a teacher. Zirconium nitride. So we've looked at two properties there
0:26:45   and used them to screen a large sesh of possible precursor molecules on identify Plea once the best
0:26:54   fish, those two properties. So to summarize high throughput computation is a useful strategy to
0:27:04   screen in a very large chemical space on narrow down that space into candidates molecules that could
0:27:12   be looked at in more detail. Computational E with really fine detailed studies or can be passed over
0:27:18   to experimental studies synthesized and tested in reactor. We could also guess chemical insights by
0:27:27   looking at the whole range of molecules and seeing the trends. In this case, we saw that the
0:27:32   electron withdrawing groups like Sanoh had a strong effect on their neighboring Liggins, making
0:27:37   stronger where the Biden Tate Liggins made the weaker. So we saw quite surprising effects within the
0:27:45   organ, a metallic complex where the thermal stability really depended on the particular mix of legal
0:27:51   that were present. So this is a useful technique for all manner of materials. Were trying to shift
0:28:00   the
0:28:05   level of difficulty to the computer on have robust and easy to use work flows for people to use the
0:28:12   computer to do screening more quickly. Guess to a small set of compounds that are gonna be
0:28:17   successful experience.
0:28:21   Thank you for attending the talk. Do please ask questions asses. The P A L D event proceeds and
0:28:30   please. Also, if you want to reach out, fire our websites www dot shorting ordered dot coms or by
0:28:38   email to me on Do I look forward to discussing this with you further? Thank you.