What is computational physics? (Wired article)

A recent Wired article addresses the question of whether computational physics is experiment or theory. Computational physics, also commonly called modeling or simulation, plays a large role in modern research, including my own.

If we agree on the fundamental ideas of science, then we can have a discussion on the role of computational science. Let me give the following (very brief) overview of science:

The Nature of Science: Science is all about models. We look at something in real life and try to make a model of it. We can use this model to predict future (or new) events in real life. If the model doesn’t agree with real data, we change the model. Repeat forever.

Read the clearly written full article at Wired:

A neutrino measurement to watch

Great science writing, and fascinating physics:

"At the end of the day, neutrinos are weird. They hang out in the quantum realm, a land of probabilities and mixing matrices and other shenanigans. But here’s what you should know. There are lots of different things we can measure about neutrinos—and one of them is a parameter called theta13 (pronounced theta one three). Theta13 relates deeply to how neutrinos mix together, and it’s here that scientists have seen the faintest hint of disagreement from different experiments."




Quantum biology

Quantum biology is the study of if and how quantum effects play a role in biological organisms, traditionally considered too warm, big and messy for them to matter. Recent research has, however, started to uncover that several biological systems do exhibit interesting quantum effects.

This TED talk by Jim Al-Khalili probably won't surprise you if you have been following the field as I have, but it is a superb recap and introduction to the topic.

"How does a robin know to fly south? The answer might be weirder than you think: Quantum physics may be involved. Jim Al-Khalili rounds up the extremely new, extremely strange world of quantum biology, where something Einstein once called “spooky action at a distance” helps birds navigate, and quantum effects might explain the origin of life itself." via TED Talks

New website and upgraded blog

After some consideration, I finally made the effort to get myself a proper domain (mostlyphysics.net), and move my personal web page to a brand-spanking-new Squarespace hosting.

The blog has also moved here from Wordpress, and hopefully I'll manage to update it a bit more often than in the past year – perhaps the extra bells and whistles that this website allows will make it more interesting. 


Calculating the graphene C 1s core level binding energy


I have a new article just out, published as a Rapid Communication in Physical Review B. The work is a computational study co-authored with Duncan Mowbray and Mathias Ljungberg from San Sebastian, Spain, and Paola Ayala from Vienna.

As described in the post about my recent review article, X-ray photoelectron spectroscopy is an extremely useful tool for studying the composition of nanomaterials. However, to correlate measurements to actual atomic structures, we need to know their binding energies. In this work, we systematically calculate the core level binding  energy of graphene using two different methods, as described in the abstract:

X-ray photoelectron spectroscopy combined with first-principles modeling is a powerful tool for determining the chemical composition and electronic structure of novel materials. Of these, graphene is an especially important model system for understanding the properties of other carbon nanomaterials. Here, we calculate the carbon 1s core level binding energy of pristine graphene using two methods based on density functional theory total energy differences: a calculation with an explicit core-hole, and an all-electron extension of the delta self-consistent field (ΔSCF) method. We study systematically their convergence and computational workload, and the dependence of the energies on the chosen exchange-correlation functional. The ΔSCF method is computationally more expensive, but gives consistently higher C 1s energies. Although there is a significant functional dependence, the binding energy calculated using the PBE functional is found to be remarkably close to what has been measured for graphite.

You can find the article on the PRB website, or in manuscript form on arXiv.

Graphene: The quest for supercarbon

Mark Peplow has written a good primer for Nature News about the European Union's Graphene Flagship initiative, which will fund graphene research to the tune of 1 billion euros over the next 10 years as part of the Horizon 2020 funding program. The story is also covered in a segment of the latest Nature podcast.

Many of the people quoted in the article are, understandably, very active in the nanocarbon research community, and I've had the pleasure of meeting them or at least hearing most them talk.

See also a video introducing the project featuring the Mr. G character mentioned in the story:


Moving to Vienna for a postdoc (VP1)

From: http://www.traveldiscounters.ca/Travel-Vacations/Vienna-Austria-Travel.php

After finishing one's PhD, it is typical that budding scientists spend a period doing research abroad. Cue Wikipedia:

Postdoctoral research is scholarly research conducted by a person who has completed doctoral studies. It is intended to further deepen expertise in a specialist subject, including integrating a team, acquiring novel skills and methods. Postdoctoral research is often considered essential while advancing the scholarly mission of the host institution; it is expected to produce relevant publications.

A single such period spent in one place is colloquially called "a postdoc", and typically is one to two years in duration. It is common to spend several of these, often moving from place to place, accruing experience, publications, and applying for tenure track positions in ones native country (or anywhere). In practice, having postdoctoral experience from abroad is a de facto prerequisite for tenure positions in Finland, and in many other countries as well.

Well, I finished my PhD already in 2011, and have been doing a postdoc in the same university ever since. Mine was a exceptional case: I was involved in managing a couple of research projects, and responsible for a large international conference being held this June. After that is done, I'll take a well-deserved summer holiday, and the move to Vienna, Austria for a two year postdoc. Luckily I have also gotten some research done, but I really look forward to being able to concentrate on it more.

I thought it would be interesting to share my experiences of the process. I've lived in Helsinki my whole life, and despite having traveled quite a bit, moving abroad is not an insignificant step. Especially to a country whose language I don't speak (I had Russian instead of the typical French or German in school)! On top of that come considerations typical for my career stage: where to get funding, how to choose where to go (both professionally and personally), what to study (what is interesting to you vs. what gets funded), and so on. Luckily I was already able to secure a postdoc grant for the entire period, which will be the topic of my next post.

I am planning on writing a series of blog posts on all aspects of this transition, hopefully offering some useful advice for people who are pondering the same issues. I'll mark the posts by a running "(VP#)" numbering in the titles for easy reference. If you have any particular aspect you would like to read about, please let me know!