Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Livermore scientists predict novel melt curve of hydrogen

07.10.2004


Scientists at the Lawrence Livermore National Laboratory have discovered a new melt curve of hydrogen, resulting in the possible existence of a novel superfluid - a brand new state of matter


This figure illustrates the transition from a molecular solid (top) to a quantum liquid (bottom) that is expected to occur in hydrogen under high pressure.



As reported in the Oct. 7 edition of the journal Nature, the researchers present the results of ab initio calculations of the hydrogen melt curve at pressures up to 2 million atmospheres.

The measurement of the high-pressure phases of hydrogen has been the focus of numerous experiments for nearly a century. However, the phase boundary that separates the solid and the liquid has remained relatively unknown.


Until now, when scientists Stanimir Bonev, Eric Schwegler, Tadashi Ogitsu and Giulia Galli reported the melt line with first principles simulations, and proposed new experimental measurements to verify the existence of a maximum melting temperature and the transformation of solid molecular hydrogen to a metallic liquid at pressures close to 4 million atmospheres.

“Our results show that a quantum fluid at around 4 million atmospheres of pressure is possible, at very low temperature” Bonev said. “Contrary to intuitive expectations, we discovered that the melting temperature versus pressure curve has a maximum, which is not directly related to molecular disassociation, but rather to changes in the intermolecular interactions in the fluid phase, occurring at high pressure”

The Livermore team’s calculations not only predict a maximum in the melt line, but also provide a microscopic model showing its physical origin in changes in the intermolecular interaction - significantly different from earlier models. Based on their new understanding for the physics behind the melting of hydrogen, the researchers are able to propose new experiments to measure the solid-liquid phase boundary.

The calculated melt curve of hydrogen is between 500,000 atmospheres and 2 million atmospheres of pressure. Above about 800,000 atmospheres of pressure, the melt line goes from a positive to a negative slope - a phenomenon that is related to a softening of the intermolecular interactions and to the fluid and solid becoming very similar in structure and energy at high pressure. This change from a positive to a negative slope is gradual and is not directly related to molecular disassociation, as previously speculated.

“Our results provide strong evidence toward the existence of a low-temperature quantum fluid in hydrogen,” Bonev said. “The existence of a maximum melting temperature is a unique physical phenomenon in a molecular solid with a close packed structure.”

The simulations carried out by the Livermore team are very complex and sophisticated, and required the use of large-scale parallel quantum simulation codes, such as the LLNL GP ab-initio molecular dynamics code, written by F.Gygi in the Computation Directorate.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov
http://www.nature.com

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>