ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarPalotás KrisztiánWigner RCP SZFIRevised Chen's derivative 
rule for efficient simulations of scanning tunneling microscopy and some 
recent applications (Publication Prize talk)Tuesday, 8 February 2022, 10:00, 
Bldg 1, auditorium,  
https://wigner-hu.zoom.us/j/99126621753?pwd=UmZsRlJDM3BxMk1nVkJ5YWc5R0tIZz09  
 Meeting ID: 991 2662 1753  Passcode: 202361Scanning tunneling microscopy 
(STM) is a widely used experimental method in surface science to investigate 
and manipulate material surfaces at the atomic scale, employing the quantum 
tunneling of electrons. Advanced simulation tools of experimental STM are 
vital for the proper understanding of the physical and chemical processes 
involved in the imaging/manipulation. For this reason Chen’s derivative rule 
for electron tunneling has been revised [1] for the purpose of 
computationally efficient simulation of STM based on ab initio electronic 
structure calculations. New features include (i) the weighting of tunneling 
matrix elements of different tip-orbital characters by an arbitrary 
energy-independent choice or based on first-principles data, (ii) arbitrary 
tip geometrical orientations to mimick asymmetric tip-sample relations, and 
(iii) the possibility of quantitative analysis of tip-orbital interference 
contributions to the tunneling current. The simulation model has initially 
been applied to two functionalized surfaces where quantum interference 
effects play an important role in the STM imaging and the Tersoff-Hamann 
(spherical tip orbital) model fails to describe the correct STM contrast 
under certain conditions: N-doped graphene and a magnetic Mn2H complex on the 
Ag(111) surface [1]. Recently, the revised Chen’s STM simulation method has 
been applied to diverse complex surface oxide [2,3,4] and iodide ultrathin 
films [5], where a better agreement with experiments has been achieved than 
obtained with the Tersoff-Hamann method. Other examples of our contributions 
to understand recent STM experiments will also be briefly listed.[1] G. 
Mándi, K. Palotás, Phys. Rev. B 91, 165406 (2015).[2] T. Lee, Y.-J. Lee, K. 
Palotás, G. Lee, C. Stampfl, A. Soon, Nanoscale 11, 6023 (2019).[3] T. T. 
Ly, T. Lee, S. Kim, Y. J. Lee, G. Duvjir, K. Jang, K. Palotás, S. Y. Jeong, 
A. Soon, J. Kim, J. Phys. Chem. C 123, 12716 (2019).[4] Y.-J. Lee, T. T. Ly, 
T. Lee, K. Palotás, S. Y. Jeong, J. Kim, A. Soon, Appl. Surf. Sci. 562, 
150148 (2021).[5] G. Lee, Y.-J. Lee, K. Palotás, T. Lee, A. Soon, J. Phys. 
Chem. C 124, 16362 (2020). Minden érdeklődőt szívesen látunk! - Everyone 
is welcome to attend.Róbert Juhászsem-admin AT szfki.hu