Postdoctoral Researcher  •  Research Center for Applied Sciences (RCAS), Academia Sinica, Taiwan

March 2023 - December 2024

• Developed hybrid Monte Carlo code from the ground up in Python programming language leveraging LAMMPS for molecular dynamics runs and energy evaluations during every trial move in 2D Ruddlesden-Popper perovskite layer exchange simulation. Adapted the code to run both on the GPUs and CPUs, employing updated machine-learned interatomic potential based on the bispectrum descriptor, as implemented in the Spectral Neighbor Analysis Potential (SNAP). The code running on the GPU enabled 10 fold increase in computation speed compared to the CPU version;
- from series of layer exchange simulations extracted the relevant data which matched the currently available experimental results and explained the difference between odd and even 2D perovskite members which was lacking in previous studies. The manuscript including results from this study is being finalized for submission to a relevant scientific journal;
# Results from the simulations were presented at the Materials Research Society (MRS) Conference in Singapore (05-2023) and International Conference on Molecular Simulation (ICMS) in Taipei, Taiwan (10-2023);

• Performed on-the-fly Machine Learning Ab-initio Molecular Dynamics (ML-AIMD) simulations in Vienna Ab-initio Simulation Package (VASP) of lithium intercalation in halogen decorated nanographene flake in Li-ion battery anode material and large-scale molecular dynamics simulations using Matlantis machine learning enabled potential.
- from the series of calculations the data confirmed higher capacity of fluorine decorated nanographene flakes compared to the other halogens which was verified by the experiments. In addition, simulations revealed the preferential adsorption sites of Li atoms which is an additional insight not accessible by the current state-of-the-art experimental methods;
# Results from this study were published in a reputable scientific journal;

• Performed a series of supercell optimization and band structure calculations in VASP with an aim to explore the phase transition of inorganic double perovskite material with different level of doping.
- obtained results were in excellent agreements with the experimental data verified by the collaborating group. In addition, band structure calculations explained the indirect band gap detected experimentally; 
# The manuscript with results obtained from this study is being finalized for submission to a relevant scientific journal; 

* all calculations carried out on Taiwania I, II and III supercomputers;

* National Science and Technology Council (NSTC) postdoctoral fellowship

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@ Computational Nanomaterials & Nanomechanics Lab

Doctoral Candidate  •  Research Center for Applied Sciences (RCAS), Academia Sinica, Taiwan

August 2017 - February 2023

• Developed a Grand Canonical Monte Carlo (GCMC) 2D perovskite crystal growth simulation code from the ground up in Python programming language, employing the machine-learned potential, leveraging PyLammps library as an interface to LAMMPS molecular simulation package for energy evaluations of the supercell structures during the trial moves. Discovered a memory leak in the third party API and provided an alternative solution;
- The simulations matched the available experimental results showing pyramid like growth of 2D perovskite material. In addition, the shape of the pyramid structure was dependent on the chosen value of the chemical potential as an input which is an information that provides a useful material synthesis guideline leading to better control in growing 2D perovskite crystal;

• Successfully trained a machine-learning enabled potential for butylammonium (BA) based 2D perovskite material employing the Behler-Parrinello feed-forward neural network (FFNN) method based on the Gaussian descriptor as implemented in Atomistic Machine-learning Package (AMP);
- The fidelity of the machine learning potential is validated from energy and force parity plots, while the force-field stability is verified from molecular dynamics simulations;

• Assembled a relevant training set from ab-initio molecular dynamics trajectories (AIMD) including the most important inter-atomic contributions in 2D perovskite material as an input for the subsequent machine learning of the artificial neural network (ANN) force-field;

• Carried out a series of density functional theory (DFT) energy optimizations of relevant low-index facets in 2D Ruddlesden-Popper material;
- extracted surface features revealed that relatively low surface energies stem from hydrogen bond shortening increasing the strength of Coulomb interaction between organic cations and iodine atom. In addition, Wulff constructions of equilibrium crystal shapes were in excellent agreements with available experimental results;
# results presented at the WCCM ECCOMAS Conference in Paris, France (01-2021);

• Performed a DFT study of adsorption of small organic molecule on lead-free antimony-based all-inorganic perovskite;
- calculations revealed noticeably stronger affinity of O atom within the N-methylpyrrolidone (NMP) molecule to Cs atom in all-inorganic Cs3Sb2I9 perovskite compared to S atom within thiourea (TU) leading to better morphology and increased stability of the active layer of the solar cell device. This insight from the DFT calculations explained the difference in stability of the film treated with NMP and TU confirmed by the collaborating experimental group;

• Carried out large scale DFT study of intertwined defect in 2D layered Ruddlesden-Popper 2D perovskite material in VASP,
- energy evaluations revealed decreasing trend with increasing 2D perovskite member. Extracted band structure and density of states (DOS) of the resulting supercells reveal shallow defects and Fermi level pinning features in the material, implying that this defect should be avoided by choosing adequate material fabrication methods;

* all calculations carried out on Taiwania I, II and III supercomputers;

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@ Computational Nanomaterials & Nanomechanics Lab

Graduate Researcher  •  Research Center for Applied Sciences (RCAS), Academia Sinica, Taiwan

March 2016 - July 2017

• Carried out metadynamics simulations of methylammonium lead-iodide (MAPbI3) soft crystal using DL_POLY Classic molecular dynamics simulation software;
- extracted the free energy surface (FES) and the energy barrier for crystal nucleation from amorphous phase at different temperatures which provided an insight into the nucleation of the perovskite crystal at nanoscale;
# results including the energy barriers and critical nuclei presented at the Association of Computational Mechanics Conference (ACMT) in Tainan, Taiwan (10-2017)};

• Carried out a Temperature Accelerated Dynamics (TAD) simulations of cation defect in MAPbI3 crystal in LAMMPS molecular dynamics simulator;
- the results revealed different diffusion barriers and cation pathways depending on whether an external electric field was applied. This distinction is an important feature for experimental groups considering perovskite materials as active layers in capacitor devices;

• Performed a series of molecular dynamics simulations of methylammonium lead-iodide (MAPbI3) soft crystal, in both LAMMPS and DL_POLY Classic simulation packages;
- the test revealed no difference in the phase stability and temperature limits of the MAPbI3 interatomic potential, thus verifying the fidelity of the perovskite force-field. While the computational speed of LAMMPS was better, DL_POLY Classic proved to be more suitable for simulating the phase transition by employing the built-in metadynamics module;

* all simulations carried out on local cluster including 16 core and 12 core notes

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@ Computational Nanomaterials & Nanomechanics Lab

Graduate Researcher  •  Research Center for Applied Sciences (RCAS), Academia Sinica, Taiwan

April 2015 - February 2016

• Initiated experiments with an aim to investigate cellular responses in hypoxic environment generated by spatially controlled chemical reactions within the PDMS-based microfluidic device;
- the initial results obtained from the experiment revealed cell migration within the microfluidic device under the oxygen gradient confirming findings of previous studies;

• Performed the simulation tests of the flow regime in the microfluidic device using COMSOL Multiphysics simulation package;
- the results predicted stable laminar flow in the designed microfluidic device, which was necessary for conducting the subsequent experiments;

• Fabricated PDMS-based microfluidic devices for hypoxia study;

• Cell culture - passaging cells on daily basis;

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@ Lab for Integrated Biomedical Microdevices

Graduate Researcher  •  Academia Sinica, Taiwan

October 2014 - April 2015

• Lab rotation @ Molecular and Material Modeling Lab [Institute of Atomic and Molecular Sciences] (02-2015 - 04-2015),
- conducted a comprehensive literature review of available classical H2O force-field models (TIP3P, TIP4P) to study phase transition in water from molecular dynamics simulations;

• Lab rotation @ Polymer Physics and Complex Fluids Group [Institute of Physics] (09-2014 - 01-2015),
- conducted a literature review of DNA in nanoconfinement from molecular dynamics simulations,
- conducted a literature review and proposed a project for polymer-based solar cell active layer material study from molecular dynamics simulations;

Software [Chemical] Engineer, Early stage researcher  •  Centre for Research & Technology Hellas (CERTH), Thessaloniki, Greece

October 2012 - December 2013

• Developed a working beta version of a polystyrene batch reactor stand-alone application integrating both front-end in C#, and back-end in Fortran programming language using Microsoft Visual Studio,
- further facilitated a simulation of the batch reactor output based on the chosen input parameters improving on the previous solution;

• Developed a polystyrene CAPE-OPEN compliant batch reactor unit operation using C# programming language,
- this allowed the underlying reactor mathematical model to be applied in industry standard CAPE-OPEN compliant chemical engineering process simulation packages (Aspen Plus, COCO Simulator);

• Developed an interface to a polystyrene batch reactor using Visual Basic for Applications (VBA) and Excel as a front-end for parameter input,
- the solution was successfully presented as an intermediate working model to BASF (a chemical industry partner on the project);

* Under the 'Multimod' [Multiscale modeling] project hosted by the Aristotle University of Thessaloniki, Marie Curie fellowship

Biochemical analyst  •  University Clinical Center Nis, Serbia

March 2012 - May 2012

• Blood serum analysis, Olympus blood analyzer operator,
- handled the blood samples, classified obtained results;