Linear scaling DFT modelling of ferroelectrics

Lead Research Organisation: University College London
Department Name: Physics and Astronomy


We will develop and apply the CONQUEST linear scaling DFT code to modelling the properties of ferroelectric materials. The project will consist of development work, initially focussing on the efficient distribution of workload onto different processing architectures, and on the properties of large-scale defects, such as domain walls, on the properties of ferroelectric materials.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509577/1 30/09/2016 24/03/2022
1783919 Studentship EP/N509577/1 30/09/2016 29/09/2020 Jack Stephen Baker
Description The world's most used piezoelectric material (a material which produces a current when you squeeze it) lead zirconate titanate has a crystal structure which may repeat in a unit cell containing thousands of atoms. Further, approximations used to study crystals with such properties have been demonstrated to be quantitatively wrong. One such approximation (the so called "virtual crystal approximation") has been demonstrated to show distortions in the crystal which are fictitious when compared to a real calculation.

Another finding is that thin ferroelectric (materials which are electrically polarised in the absence of an applied electric field) films of lead titanate prefer to organise their polarisation into stripe domains above 5 unit cells in depth. Below this depth, they are organised in a single domain along a diagonal in-plane axis, supported by an interconnected network of oxygen octahedral rotations. This is important as it helps us minaturise devices relying on ferroelectricity (like ferroelectric memory, used in games consoles and other technologies)

We have also found that ferroelectric crystals which require large-scale simulations based on quantum mechanics can be simulated using the CONQUEST code. Usually, these materials are not studied with this type of methodology since the accuracy is not high enough. We have demonstrated that our method in the code is accurate enough however allowing us to solve complex problems that were previously insoluble with the method.
Exploitation Route Others may want to use our methodology to solve the plethora of problems in the ferroelectric perovskite oxides which were previously insoluble using a quantum mechanics based approach.

Our work with thin films of lead titanate could inform industry of the challenges associated with minaturising devices based on ferroelectric memory.

Our work on the piezoelectric material lead zirconate titanate could inform industry on how to enhance the the current produced by the material upon straining (squeezing) it.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Manufacturing, including Industrial Biotechology