1. The DFT-calculation of Potassium doped Picene Kotaro Yamada Kusakabe labolatory

2. Contents Introduction. ・ experimental article ・ what I can do ・ How to Main part. ・・・ As a result ・ output datum of K 3 Picene. ・ output datum of K 2 Picene Summary & Future work

3. Experimental article Pristine Picene Kx-Picene (x=3.3) Tc = 18K R. Mitsuhashi, et. al. Nature 464 (2010) 76. introduction

4. Image of pristine and doped Picene organic semiconductor Superconductor Potassium Picene G. Giovanetti et al.: Phys. Rev. B 83 (2011) 134508. introduction

5. A contraversy Kubozono group “K 3 Picene is superconductor ” Vs Sawa group “most of samples are K 2 Picene and semiconductor by Xray observation” Each statement can’t be denied

6. What can I do for this subject?? ・ Logical calculation. ・ To interpret the datum ・ To state a hypothesis. introduction

7. Logical calculation possible model in meta stable state. introduction

8. How to

9. input data ・ Relax calculation Atomic structure ・ band calculation band structure Fermi surface Output data Based on the density functional theory. Quantum espresso

10. Dimensionality of Fermi surface 1dimension 2dimension3dimension

11. carbon hydrogen Herring bone structure a b c Example of atomic structure

12. Condition

13. 8.480 6.154 13.515 5.035 Unit cell parameter for K 3 Picene Cell parameter 1 monoclinic R. Mitsuhashi, et. al. Nature 464 (2010) 76. Kubozono group presented Unit cell parameter a=8.480,b=6.154,c=13.515in Å

14. Unit cell parameter for K 2 Picene 7.9302 7.6386 12.9655 Cell parameter 2 orthorhombic ＊ 2;T. satou et al.: 物理学会 (2011 秋 ). 24aTD-4 Unit cell parameter a=7.9302,b=7.6386,c=12.9655 in Å

15. Unit cell parameter for K 2 Picene 7.9302 7.6386 25.931 Cell parameter 3 orthorhombic ＊ 2;T. satou et al.: 物理学会 (2011 秋 ). 24aTD-4 Sawa group presented Unit cell parameter a=7.9302,b=7.6386,c=25.931 in Å

16. as a result

17. The structure of K 3 Picene with cell parameter 1 potassium Carbon (Picene) hydrogen a b c a c b

18. 6.7453 eV eV a* b* c* Γ Y T Z Γ X S R U X

19. a b a* b* c* Γ Y T Z Γ X S R U X 6.9453 eV

20. The structure of K 2 Picene with cell parameter2 a bc

21. 4.9779 eV a* b* c* Γ Y T Z Γ X S R U X

22. 5.0779 eV Γ Y T Z Γ X S R U X a* b* c*

23. 5.1779 eV a* b* c* Γ Y T Z Γ X S R U X

24. The structure of K 2 Picene with cell parameter3

25. Γ Y T Z Γ X S R U X Cell parameter 3 Cell parameter 2

26. summary ・ K 2 Picene has narrow band gap ・ K 2 Picene has different band structure in cell parameter ・ in fact potassium atoms may be localized in some layer ・ a slightly doped semiconductor may become a superconductor ・ Find any other possible meta stable state. ・ Find Fermi surface becomes the factor of superconductivity. Future work