615 reputation
213
bio website
location Oslo, Norway
age 36
visits member for 2 years, 2 months
seen Oct 3 at 17:11

I am a scientific researcher at Centre of Theoretical and Computational Chemistry at the University of Oslo. I work at the ERC funded project ABACUS, studying mainly the fundamentals of density functional theory for atoms and molecules. This involves some functional analysis, convex analysis, quantum mechanics and a little chemistry.

I also stydy numerical methods for quantum systems in general, and in particular for time evolution of the manybody Schrödinger equation.

In short: a mathematically oriented physicist with chemistry aspirations.


Sep
24
awarded  Autobiographer
Aug
24
awarded  Yearling
Jul
24
comment How to show if A is denumerable and $x\in A$ then $A-\{x\}$ is denumerable
What is the question?
Jul
9
awarded  Critic
Jul
9
comment Calculate the derivative w.r.t. a vector?
Study it componentwise. $f(v)$ is a matrix with components $f(v)_{ij}$ dependent on all $v_k$, so the derivative is a three-index quantity: $\partial f_{ij}/\partial v_k$.
Jul
8
comment Fourier series that converges in $L^2$ but not pointwise
The relevant theorem in Zygmund's "Trigonometric Series", is Theorem 4.1. The statement is: "There exists an $f\in L^1$ such that its Fourier series diverges everywhere."
Jul
7
answered Mathematicians ahead of their time?
Jul
7
comment Sobolev's inequality from Reed & Simon vol. II
I have found that indeed the Sobolev embedding theorem and the Hardy--Littlewood--Sobolev inequality are related. According to this Wikipedia page, Sobolev's original proof of the former involved the latter.
Jul
4
accepted Sobolev's inequality from Reed & Simon vol. II
Jul
4
asked Sobolev's inequality from Reed & Simon vol. II
Jul
2
awarded  Curious
Jun
13
accepted What is wrong with this “counterexample” of boundedness of weakly convergent sequences?
Jun
13
comment What is wrong with this “counterexample” of boundedness of weakly convergent sequences?
I see that now! Thanks for the answer. In the counterexamples to the decay claim, the intuitive idea is that any (square) summable sequence can be "fleshed out" with zero-strings of increasingly large size, thus slowing down convergence arbitrarily.
Jun
12
comment What is wrong with this “counterexample” of boundedness of weakly convergent sequences?
I understand: one can say $v_k/\sqrt{k}\to 0$, but not the existence of the $C>0$. Then one cannot conclude that $u_n$ converges weakly.
Jun
12
asked What is wrong with this “counterexample” of boundedness of weakly convergent sequences?
Mar
4
awarded  Nice Answer
Feb
28
comment Monotonically increasing maximum eigenvalue
But doesn't this matrix have an eigenvalue 1 for the vector $(1,1,1,1,1,1)^T$?
Feb
27
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
How about $e^{\ln 2} = 2$?
Feb
27
comment Spectral theorem in Quantum Mechanics
Reed & Simon Volume I, Section VIII.5 gives definition, theorems and examples.
Feb
20
accepted Critical points of multivariate polynomials