@inproceedings {ongkikoSPP2019,
	title = {Molecular projected band structure of ammonia and ammonium adsorbed on graphene},
	booktitle = {Proceedings of the 37th Samahang Pisika ng Pilipinas Physics Conference},
	year = {2019},
	month = {29 May 2019},
	pages = {SPP-2019-PA-17},
	address = {Tagbilaran City, Philippines},
	abstract = {The electronic structures of ammonia and ammonium molecules adsorbed on pristine graphene are studied in this work. In particular, molecular projected densities of states (MolPDOS) were calculated by density functional theory to characterize these adsorption systems by projecting the eigenstates of the full system onto those of the adsorbate molecule. Ammonium adsorption on graphene exhibited a stronger adsorption than ammonia, indicating the possibility of designing a selective substrate. This difference was also reflected in the MolPDOS-produced band structure by the presence of distinct regions of mixed ammonium and graphene states located around 1 eV above the Fermi level.},
	url = {https://paperview.spp-online.org/proceedings/article/view/SPP-2019-PA-17},
	author = {Mario Antonio T. Ongkiko and Francis N. C. Paraan}
}
@inproceedings {476,
	title = {Band structure contribution of adsorbed H$_{2}$ on graphene calculated from molecular orbital projections},
	booktitle = {Proceedings of the 36th Samahang Pisika ng Pilipinas Physics Conference},
	year = {2018},
	month = {6{\textendash}9 June 2018},
	pages = {SPP-2018-PA-19},
	address = {Puerto Princesa City, Philippines},
	abstract = {<p>Density functional theory allows for the first-principles calculation of projected wavefunctions onto orthogonalized atomic wavefunctions. Such calculations can be applied to study the bonding of a molecule onto an adsorbing surface. In particular, these projections allow one to identify the contributions of the adsorbed molecule to the band structure of the whole system. In this paper, we consider a system composed of an H<sub>2</sub> molecule adsorbed onto the hollow (H) site in a graphene 3x3 supercell. The adsorbed H<sub>2</sub> molecule gives rise to two bands roughly 6 eV on either side of the Fermi energy. These bands may be attributed to the hybridization of the H<sub>2</sub> bonding and anti-bonding molecular\&nbsp;<span style="color: $\#$545454; font-family: arial, sans-serif; font-size: small;">σ</span>\&nbsp;orbitals and the graphene bands.</p>},
	url = {https://paperview.spp-online.org/proceedings/article/view/SPP-2018-PA-19},
	author = {Mario Antonio T. Ongkiko and Francis N. C. Paraan}
}