Lee Hsun Lecture Series

Topic: Computational Materials Discovery: New Developments and Surprising Discoveries

Speaker: Prof. Artem R. Oganov
           Stony Brook University, USA

Time: 10:00-12:00 AM., (Mon.) Jul. 21, 2014

Venue: Room 403, Shi Changxu Building, IMR CAS

Abstract:

Thanks to powerful evolutionary algorithms, in particular to the USPEX method [1-3], it is now possible to predict both the stable compounds and their crystal structures at arbitrary P,T-conditions, given just the set of chemical elements. Recent developments include the extension of this algorithm to molecular crystals [4] (which allowed large structures to be handled easily, leading to revision of high-pressure structures of Mg(BH₄)₂ [5], proving earlier proposed “experimental” structure to be incorrect) and a new technique called evolutionary metadynamics [6]. Some of the results that I will discuss include:

1. Theoretical and experimental evidence for a new stable high-pressure phase of boron, γ-B [7], showing superhardness and charge transfer between boron atoms. 
2. New insulating and optically transparent, and experimentally confirmed, form of sodium [8]. 
3. Establishment of the structure of a carbon allotrope – M-carbon [1,9]. 
4. Predicted reactivity of noble gases under moderate pressures – Xe [10] and even He. 
5. Predicted stability of “impossible” chemical compounds – such as Na3Cl, Na₂Cl, Na₃Cl₂, NaCl₃, NaCl₇ [11], Mg₃O₂ and MgO₂ [12]. These compounds become stable under pressure and we already have compelling experimental evidence for some of them [11].

References

[1] Oganov A.R., Glass C.W., J.Chem.Phys.124, 244704 (2006).
[2] Oganov A.R., Lyakhov A.O., Valle M., Acc. Chem. Res. 44, 227-237 (2011). 
[3] Lyakhov A.O., Oganov A.R., Stokes H.T., Zhu Q., Comp. Phys. Comm.184, 1172-1182 (2013).
[4] Zhu Q., Oganov A.R., Glass C.W., Stokes H.T., ActaCryst. B68, 215-226 (2012).
[5] Zhou X.-F., Oganov A.R., Qian G.R., Zhu Q., Phys. Rev. Lett.109, 245503 (2012).
[6] Zhu Q., Oganov A.R., Lyakhov A.O., Cryst.Eng.Comm.14, 3596-3601 (2012).
[7] Oganov A.R., Chen J., Gatti C., et al., Nature457, 863 (2009).
[8] Ma Y., Eremets M.I., Oganov A.R., et al., Nature458, 182 (2009).
[9] Boulfelfel S.E., Oganov A.R., Leoni S., Scientific Reports 2, art.471 (2012).
[10] Zhu Q., Jung D.Y., Oganov A.R., et al., Nature Chemistry5, 61-65 (2013).
[11] Zhang W.W., Oganov A.R., Goncharov A.F., et al., Science342, 1502-1505 (2013). 
[12] Zhu Q., Oganov A.R., Lyakhov A.O., Phys. Chem. Chem. Phys.15, 7796-7700 (2013).