Abstract
In this short communication we present the main results of an ab initio structural search for new polymorphs of the group-14 elements C, Si, and Ge, with a focus on low-density and energetically favorable sp3-bonded tetrahedral polymorphs which could constitute candidate phases to be synthesized in the laboratory. We propose new orthorhombic and tetragonal polymorphs with enthalpies that are lower or comparable to those of other polymorphs of the group-14 elements that have either been experimentally synthesized or recently proposed as the structure of unknown phases obtained in experiments. The new phases have interesting structural and electronics properties. These include an orthorhombic phase that in Si is found to have a quasi-direct band gap at the zone center of about the right size for optimal photovoltaic applications, and a tetragonal phase with a chiral topology that displays an exotic pentagonal pattern and whose vibrational properties match those of an unknown phase of Si.
Export citation and abstract BibTeX RIS
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.