Vol. 94, September 7th, 2015


  • Announcement
  • Upcoming Events
  • Paper of the week

Paper of the week

Toshiaki Iitaka


Water molecule survives in highest pressure ice

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.


"Software developed at RIKEN's Interdisciplinary Theoretical Science is mentioned in Nature (Feb. 2015)."
See, http://www.nature.com/news/programming-pick-up-python-1.16833

Upcoming Events

iTHES Colloquium

September 15th (Tue.) 15:00-
"Numerical Weather Prediction: Chaos, Predictability and Data Assimilation"
Dr. Takemasa Miyoshi(RIKEN AICS)
Place: 2F Large mtg.rm, Main Cafeteria (Bldg. C61)
???? Contemporary weather forecasting is based on numerical simulations with supercomputers, i.e., numerical weather prediction (NWP). The weather system is chaotic, and data assimilation plays a central role in predicting the chaotic weather by synchronizing a numerical simulation with the real world. Data assimilation integrates simulations (i.e., virtual world on computers) and real-world data based on statistical mathematics and dynamical systems theory, and brings synergy. Although data assimilation for large-scale computational problems has been evolving extensively in the field of NWP, data assimilation is a general approach potentially applied to a wide range of simulation studies. This lecture provides an introduction to NWP and data assimilation, and discusses the future perspectives of data assimilation research in the forthcoming “Big Data” and “Big Simulation” era.

RIKEN Nishina Center - RIKEN? iTHES - RIKEN CEMS joint seminar

"The Chiral Magnetic Effect: from Quark-gluon Plasma to Dirac Semimetals"
Prof. Dima Kharzeev (Stony Brook Univ. and Brookhaven Natonal Lab.)
Date: Sep. 24, 2015.? 13:30-15:00
Place: Okochi Hall
???? Recently discovered 3D Dirac and Weyl semimetals possess massless chiral quasi-particles,? and are affected by the triangle anomalies. Quantum anomalies can induce novel? non-dissipative transport phenomena in these materials - so-called "chiral magnetic" and "chiral vortical" effects.
???? I will discuss the theory of anomalous transport, the experimental evidence from heavy ion collisions at RHIC and LHC, and the recent experimental observation of the chiral magnetic effect in Dirac semimetals.

The 6th iTHES Academic-Industrial Innovation Lecture

Date: Oct. 22(Thurs.)? 15:00-16:30
Place: TBA
Speaker: Hironori Kokubo (Takeda Pharmaceutical Company)
Title: TBA

iTHES Colloquium in November 2015

Date: Nov.10 (Tues)? 15:00-16:30
Place: big conference room (2nd floor of the main cafeteria)
Speaker: Kazuyuki Aihara (Univ. Tokyo)
Title: TBA

Fundamental Physics Using Atoms 2015
- Towards better understanding of our matter universe -

Nov. 30 (Mon.) -- Dec. 1 (Tue.), 2015
Oral sessions: RIKEN Wako, Okochi Hall (C32)
Poster sessions: Welfare and Conference Bldg. 2F (C61)

???? Recently much effort has been directed to investigation of the fundamental physics which exploits remarkable developments in atomic physics and/or quantum optics techniques. Examples include (A) test of the time reversal invariance by observing permanent electric dipole moments of atoms or molecules, (B) neutrino mass spectroscopy using atoms, (C) measurement of fine structure constant's time dependence with precession atomic clock etc. This conference aims to bring together recent research results, to discuss future prospects, and to expand research network, making this field more active and productive.

Paper of the week


Water molecule survives in highest pressure ice?
Toshiaki Iitaka

Ice is abundant in the universe: The two ice giants, Uranus and Neptune, orbiting the Sun at large distance are mainly made from ices. Orbiting beyond the ice giants are the icy bodies called Kuiper belt objects. Puto, a dwarf planet, is one of them. Outside of the Solar system exist many ice giants of various mass, radius and temperature. The phase diagram of ices is indispensable for understanding the structure and evolution of these ice giants[1] as the phase diagram of nuclear matter is for neutron stars.
Neutron diffraction is a powerful tool to study the phase diagram of ice because it can clearly see the hydrogens in ice, which X-ray diffraction cannot. A US team recently reported the neutron measurement up to the highest pressure of 52 GPa and room temperature[2]. They argued that the half of water molecules is dissociated above 26 GPa. This discovery surprised the ice scientists, who believed in that the hydrogens remain bonded to the oxygen up to 6,000 GPa.
Our international team re-examined[3] their result by using first principle electronic structure calculation at HOKUSAI-Supercomputer System, Riken and X-ray Raman spectroscopy at SPring-8, Hyogo, Japan, which probes the local electronic structure of atoms by measuring the energy loss distribution of the scattered X-ray. The characteristic feature theoretically predicated for dissociated water molecules did not appear in the spectrum measured at 50 GPa, indicating clearly that water is not dissociated at this pressure and room temperature.
[1] L. Zeng, and D. Sasselov, Astrophys J 784, 96 (2014).
[2] M. Guthrie, R. Boehler, C. A. Tulk, J. J. Molaison, A. M. dos Santos, K. Li, and R. J. Hemley, Proc. Natl. Acad. Sci. U. S. A. 110, 10552 (2013).
[3] T. Iitaka, H. Fukui, Z. Li, N. Hiraoka, and T. Irifune, Sci. Rep. 5, 12551 (2015).