The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"
description
Transcript of The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"
![Page 1: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/1.jpg)
Tue.27 Nov. Wed.28 Nov. Thu.29 Nov.
8h30 - 9h45Topical lecture
Planets / High PressureTopical lecture
Atmospheric physics
Methods: Ab-initio Molecular
Dynamics
9h45 - 10h15 Coffee break
10h15 -11h30Methods
Plane waves, cut-off, k-points, pseudopotentials, DFT, etc
Seminars Computer Lab 3
11h30 – 13h30 Lunch time
13h30 – 16h00 Computer Lab 1 Computer Lab 2 Computer Lab 4
The 6th School on Simulation and Modeling Physics"Ab-initio methods and their applications" Hanoi, 27 - 29 November 2007
![Page 2: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/2.jpg)
Exploring planetary interiors by ab-initio molecular dynamics
6th SMP, Hanoi, Nov 27-29, 2007
Sandro Scandolo(the Abdus Salam ICTP, Trieste, Italy)
![Page 3: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/3.jpg)
The Abdus Salam International Centre for Theoretical Physics(under UNESCO / IAEA), Trieste, Italy
ICTP’s mission:
To foster the growth of advanced studies and research in physics and mathematics, especially among researchers from developing countries
Opportunities
- Conferences / Schools throughout the year
- Associates (our faculty “in the field”)
- Visitors (junior, STEP, TRIL, etc)
- Diploma Course
www.ictp.it
![Page 4: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/4.jpg)
Materials SciencePlanetary Science
High pressure in
1951: the first man-made diamonds
1991: Earth’s core conditionsreproduced in the laboratory
![Page 5: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/5.jpg)
Shock waves Diamond anvil cell
![Page 6: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/6.jpg)
Approximations
- Born-Oppenheimer - Classical nuclei- Density functional theory
from “first principles”
Variable-cell molecular dynamics
[Parrinello & Rahman, 1981]
![Page 7: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/7.jpg)
Outline
High Pressure in Materials Science:
+ “Carbonia”: a silica-like CO2 amorph+ Novel transition metal nitrides
High pressure in Planetary Science:
+ Carbon in planetary interiors+ Melting of iron
![Page 8: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/8.jpg)
Silica-like CO2 : the crystal phases
+ Molecular CO2 predicted to tranform into a silica-like crystal at high pressure
+ Silica-like phases of CO2 predicted to be ultrahard
Molecular CO2 Candidate theoretical structures for silica-like CO2
Serra, Cavazzoni, Chiarotti, Scandolo, Tosatti, Science 284, 788 (1999)
Crystal structure of silica-like CO2
not yet determined
Is there a glass analog?
Experimental confirmation of silica-like CO2
Yoo et al, Science 283, 1510 (1999)
![Page 9: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/9.jpg)
“Carbonia”: the silica-like CO2 glass
Experimental evidence for amorphous CO2
Santoro, Gorelli, Bini, Ruocco, Scandolo, Crichton,Nature, in press (2006)
Compression by ab-initio molecular dynamics gives:
At 1000 K and 100 GPa: a crystalline phase
At 2000 K and 80 GPa: an amorphous phase
Octahedral CO6Tetrahedral CO4
![Page 10: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/10.jpg)
Platinum nitride: PtN or PtN2?
Raman shift (cm-1)
Gregoryanz et al, Nature Mat. (2004)Crowhurst et al, Science (2006)
Ab-initio calculations on structures with 1:1 stoichiometry fail to reproduce the experimentalRaman spectra
Single-bonded polymeric nitrogen
Eremets et al, Nature Mat. (2004)
Molecular N2
Polymeric N
![Page 11: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/11.jpg)
Platinum nitride: PtN2 pyriteYoung, Montoya, Lazzeri, Sanloup, Gregoryanz, Scandolo, PRB 2006
Raman spectra
X-ray diffraction
![Page 12: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/12.jpg)
MN2 with interstitial N2 units: a new class of transition metal nitrides?
Young, Sanloup, Gregoryanz, Scandolo, Hemley, Mao, PRL 96, 155501 (2006)
IrN2
Single bonded N-N
PtN2 pyrite
New “heavy” metal nitrides are superhard
Bulk modulus: 428 GPa (IrN2), 358 GPa (OsN2)
![Page 13: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/13.jpg)
H2O+CH4+NH3
Marvin Ross, “Diamonds in the sky”Nature (1981)
Methane was found to dissociate under a shock wave
Scandolo & Jeanloz, American Scientist (2003)
![Page 14: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/14.jpg)
Methane dissociation: what do simulations say
F. Ancilotto et al., Science 275, 1288 (1997)
Compressed methane Compressed methaneheated up to 4000 K
![Page 15: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/15.jpg)
Before compression After compression
Methane dissociation: the experimental confirmationL.R. Benedetti et al., Science 283, 100 (1999)
![Page 16: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/16.jpg)
Melting of Carbon
diamond liquid
BC8, SC ??
Neptune and Uranus isentrope
X. Wang, S. Scandolo, R. Car, Phys. Rev. Lett 2005
3.8
4.3
4.7
5.2
5.3-5.8
Coordination number
![Page 17: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/17.jpg)
Accuracy of DFT?: Melting of silicon
Solid
Liquid
Tm(LDA) = 1380 KTm(GGA) = 1520 KTm(meta-GGA) = 1700 K
Tm(experiment) = 1687 K
X. Wang, S. Scandolo, R. Car
![Page 18: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/18.jpg)
How hot is the centre of the Earth?
liqui
dso
lid
Inner core (solid Fe) Outer core
(liquid Fe)
Mantle
The temperature at the inner core boundary coincides with the melting temperature of Fe at 330 GPa
![Page 19: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/19.jpg)
The “optimized” potential method
“Optimized” potential at P,T
A. Laio et al, Science 287, 1027 (2000)
![Page 20: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/20.jpg)
Melting of Iron at Earth’s core pressures
Inner-Outer core boundary
A. Laio et al, Science 287, 1027 (2000)
Our results
Shock waveexperiments
Static experiments
DFT-basedcalculation byAlfe’ et al
![Page 21: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/21.jpg)
D. Stevenson, Nature 423, 239 (2003)
![Page 22: The 6th School on Simulation and Modeling Physics "Ab-initio methods and their applications"](https://reader033.fdocuments.us/reader033/viewer/2022051821/5681594b550346895dc686ce/html5/thumbnails/22.jpg)
The crew:J. MontoyaA. YoungR. RousseauC. CavazzoniY. LiangX. WangA. LaioR. Car….www.quantum-espresso.org