| The study of ferroelectricity and piezoelectricity in bio-systems provides an ex-citing combination of physics and biology,which have great potential in biosensing,disease diagnosis and treatment,inaugurated by the discovery of piezoelectric proper-ties in wood by Fukada in the 1950s.With modern advanced experimental techniques piezoelectric and ferroelectric properties of many other bio-materials have been re-cently discovered,including properties of bones,aortic walls,nails,teeth,seashells,and peptide nanotubes.However,little is known concerning the general principles depicting ferroelectric switching,owing to the complexity of biological materials.Glycine is the simplest amino acid and the basic unit of biomaterials.Therefore,the study of its ferro-electric properties is an important starting of the theoretical study of bio-ferroelectricity.we investigated the ferroelectric polarization of?-phase and two?-phases of gly-cine based on DFT and MPT.Our results predict that?-glycine should have a sponta-neous polarization of about 70.86C?cm-22 at 300 K.In addition,classical molecular dynamics simulations using PCC charges predict that the coercive electric field and curie temperature are 1 V·nm-1 and 630 K,respectively,and consistent with experi-mental evidence.We also show that the switching process agrees with the KAI model.This work reveals the ferroelectric properties of the biomaterial glycine and the microscopic mechanism of ferroelectric switching.This is an important basis for the study of ferroelectricity of biomaterials and will contribute to the application of bio-ferroelectric materials in biological,medical,and physical fields. |
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