Department of Physics and Centre for Computational Science and Engineering, National University of Singapore,Singapore 117542, Republic of Singapore;
Department of Physics and Centre for Computational Science and Engineering, National University of Singapore,Singapore 117542, Republic of Singapore;
Department of Physics and Centre for Computational Science and Engineering, National University of Singapore,Singapore 117542, Republic of Singapore;
Department of Physics and Centre for Computational Science and Engineering, National University of Singapore,Singapore 117542, Republic of Singapore;