The+20+Dollar+Challenge+Page

This page is reserved for the 20 Dollar challenges that we encounter during our discussions.
//Fine print: There are some unnecessary but unfortunately nagging real-world issues in our theoretical community. Such as, "Why is your calculated conductivity 100x greater than experiment? (or vice versa)" As Kieron observed, money can go a long way to make such issues go away. Solve one of the challenges below, and receive $20.- from the gracious donor who placed it there!//

//**Rules:** Substantial progress must be made before end of 10-week program, and preprint available within 1 year of that date. //

 * 1) //I would like to raise a 20 Dollar question: Provide a full ab-initio prediction of a member of a new class of ferroelectric material,// //which was then experimentally confirmed to be one, and is a compound// //which is not a trival derivation of a known ferroelectric material. -- Stefan//
 * 2) //Who can suggest a TDDFT functional which (i) can describe excitonic features in optical spectra similar to BSE results and (ii) comes with reasonable computational cost such that it is applicable to complex systems like organic semiconductors? - Claudia//
 * 3) //I offer a US$20 prize to whomever can devise a DFT functional that yields accurate bond lengths, energetics and vibrational properties of condensed matter and molecular systems. - John//
 * 4) //$20 for an explanation of how the uniform gas XC kernel can get the s-quantum defect of the Be atom so well.//
 * 5) //I offer $20 if you can find an existing material for which the orbital magnetization is an important part of the overall magnetization (e.g. more than 25%) AND at the same time the commonly accepted approach of integrating the moment inside spheres around the atoms leads to significantly wrong results (e.g more than 25% error) --- Timo//