Betül Pamuk Phil Allen Marivi Fernández-Serra Stony Brook University Computational Condensed Matter Group DOE Early Career grant DE-SC0003871 March Meeting 2011 Outline Ice Ih structure Zero Point Phonon Energy & Grüneisen parameter Motivation: Normal Isotope Shift Zero Point Expansion Experiments: Anomaly in Ice Ih Zero Point Contraction Results Lattice parameters Bulk modulus Dispersion curves Preliminary Results with Ice Ic 22-Mar-11 Betül Pamuk March Meeting 2011 2 Ice Ih Structure a c a Ice = O is tetrahedrally coordinated making two covalent bonds with 2 H’s of the molecule and two H-bonds with the nearest molecule. 22-Mar-11 Betül Pamuk March Meeting 2011 3 Phonon Contribution to Zero-Point The volume dependence of energy at zero point. [1] 22-Mar-11 Betül Pamuk March Meeting 2011 4 Grüneisen Parameter The zero-point correction to the lattice parameter: Grüneisen parameter [2] Bulk modulus 22-Mar-11 Betül Pamuk March Meeting 2011 5 20Ne 22Ne Frozen crystal lattice constant a0 = 4.255 Å [2] Bolz and Mauer, 1962 Batchelder, Losee, and Simmons, 1968 Phil Allen, 1994 22-Mar-11 Betül Pamuk March Meeting 2011 6 Unit Cell Volume Experiments of Ice Ih Zero Point Contraction 22-Mar-11 Betül Pamuk March Meeting 2011 D2O H2O Röttger et al., 1994. [3] 7 Ice Ih d(O---O) = 2.75 Å Slope: Γ negative!!! E. Libowitzky, 1999 22-Mar-11 Betül Pamuk March Meeting 2011 [4] 8 Tip4P-flexible Tip4P-flexible does NOT show zero point volume contraction C. P. Herrero, R. Ramirez (2011) [5] 22-Mar-11 Betül Pamuk March Meeting 2011 rOH (Ang) B. Pamuk et. al. work in progress 9 Electronic Energy vs. Unit Cell Volume Experiment 10 K DFT: SIESTA GGA: PBE revPBE + vdW Predict water density nicely (Jue et. al, 2011)[6] PBE 22-Mar-11 PBE-vdW revPBE Betül Pamuk March Meeting 2011 revPBE-vdW 10 Asymmetric stretching 4 molecules/cell Symmetric stretching Bending Libration Stretching of H-bonds Frequency less than 0 22-Mar-11 Betül Pamuk March Meeting 2011 11 Ice Ih Ice XI Non pure ice Ih : (KOH, defects needed) (Y. Tajima, T. Matsuo, and H. Suga, 1982) Phase transition at ~ 73 K Angle on x-y plane different than 60o Vector lengths on x-y plane a≠b a = 4.5019 Å, b = 7.7978 Å, and c = 7.3280 Å (A. J. Leadbetter, R. C. Ward, J. W. Clark, P. A. Tucker, T. Matsuo and S. Suga, 1985) 22-Mar-11 Betül Pamuk March Meeting 2011 12 Contribution to the Shift The sign of the slope will determine the sign of Γ. Work in progress… 22-Mar-11 Betül Pamuk March Meeting 2011 13 Preliminary Results with Ice Ic PBE High frequency modes have negative Γ!!! 22-Mar-11 Betül Pamuk March Meeting 2011 Low frequency modes are different with different fcn’als High frequency modes have similar behaviour 14 Comparing Functionals PBE predicts ~ 10% zero point contraction on H2O and 3% reverse isotope effect on the volume. 22-Mar-11 PBE-vdW ~ 7% zero point contraction on H2O and 2.5% reverse isotope effect on the volume. The experimental reverse isotope effect is 0.009%. Betül Pamuk March Meeting 2011 15 Conclusion Take into account the zero point phonon effects for lattice parameters. Isotope shift in ice Understand the most stable structure Calculate volume dependency of frequencies precisely Understand how different functionals explain ice 22-Mar-11 Betül Pamuk March Meeting 2011 16 References [1] P. B. Allen, Optical and Vibrational Spectroscopies Symposium Talk, 2010 [2] P. B. Allen, Phil. Mag. B 70, 527 (1994) [3] K. Röttger et al. Acta Cryst. B50, 644-648 (1994). [4] E. Libowitzky, Monatshefte für Chemie (1999) [5] C. P. Herrero, R. Ramirez, J. Chem. Phys. 134, 094510 (2011) [6] J. Wang, G. Román-Pérez, J. M. Soler, E. Artacho, and M.-V. Fernández-Serra, J. Chem. Phys. 134, 024516 (2011) Thank You 22-Mar-11 Betül Pamuk March Meeting 2011 17 12 molecules/cell 22-Mar-11 Betül Pamuk March Meeting 2011 18/30 Phase Diagram http://www.thefullwiki.org/Ice_harvesting 22-Mar-11 Betül Pamuk March Meeting 2011 19 Lattice Parameters and Unit Cell Volume Experiments of ice Ih Röttger et al., 1994. Lattice parameters a, and c as a function of temperature for ice Ih between 10 K and 265 K. [4] 22-Mar-11 Betül Pamuk March Meeting 2011 20 D2O H 2O Röttger et al., 1994. Unit-cell volume of ice Ih between 10 and 265 K. [4] 22-Mar-11 Betül Pamuk March Meeting 2011 21 Lattice Parameter PBE revPBE PBE-vdW revPBE-vdW Measurement (10 K) [4] a (Å) 4.39 4.52 4.44 4.56 4.49693 c (Å) 7.17 7.39 7.24 7.43 7.32109 c/a 1.633 1.635 1.631 1.629 1.628 B0 (GPa) 17.614 12.867 15.957 14.711 12.1 I. Hamada, 2010. Results of binding energy, lattice parameters, volume per molecule and bulk moduli; comparing different functionals. [6] 22-Mar-11 Betül Pamuk March Meeting 2011 22/30