Pub Date : 2015-11-11DOI: 10.1080/23311940.2016.1139435
A. Siddique, Shuo Gu, R. Witte, M. Ghahremani, Chidubem A. Nwokoye, A. Aslani, R. Kruk, V. Provenzano, L. H. Bennett, E. Torre
Abstract A study of dynamic and reversible voltage-controlled magnetization switching in ferromagnetic Co/Pt thin film with perpendicular magnetic anisotropy at room temperature is presented. The change in the magnetic properties of the system is observed in a relatively thick film of 15 nm. A surface charge is induced by the formation of electrochemical double layer between the metallic thin film and non-aqueous lithium LiClO4 electrolyte to manipulate the magnetism. The change in the magnetic properties occurred by the application of an external electric field. As the negative voltage was increased, the coercivity and the switching magnetic field decreased thus activating magnetization switching. The results are envisaged to lead to faster and ultra-low-power magnetization switching as compared to spin-transfer torque (STT) switching in spintronic devices.
{"title":"Electric field-controlled magnetization switching in Co/Pt thin-film ferromagnets","authors":"A. Siddique, Shuo Gu, R. Witte, M. Ghahremani, Chidubem A. Nwokoye, A. Aslani, R. Kruk, V. Provenzano, L. H. Bennett, E. Torre","doi":"10.1080/23311940.2016.1139435","DOIUrl":"https://doi.org/10.1080/23311940.2016.1139435","url":null,"abstract":"Abstract A study of dynamic and reversible voltage-controlled magnetization switching in ferromagnetic Co/Pt thin film with perpendicular magnetic anisotropy at room temperature is presented. The change in the magnetic properties of the system is observed in a relatively thick film of 15 nm. A surface charge is induced by the formation of electrochemical double layer between the metallic thin film and non-aqueous lithium LiClO4 electrolyte to manipulate the magnetism. The change in the magnetic properties occurred by the application of an external electric field. As the negative voltage was increased, the coercivity and the switching magnetic field decreased thus activating magnetization switching. The results are envisaged to lead to faster and ultra-low-power magnetization switching as compared to spin-transfer torque (STT) switching in spintronic devices.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2016.1139435","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-11-05DOI: 10.1080/23311940.2015.1109019
M. Ghahremani, A. Aslani, H. Elbidweihy, L. H. Bennett, E. Torre
Abstract The rate-independent stabilization of magnetic states with iterations in a Heusler alloy has been studied. The direct measurement of the adiabatic temperature change, ΔTad, of a Ni51Mn33.4In15.6 alloy near the magnetostructural phase transition is presented. The adiabatic temperature change at a given temperature within the temperature range of the magnetostructural transition is history dependent and varies considerably with the iteration count of the field cycle. The data show the transition from the low magnetization state to the high magnetization state during low to high (L–H) temperature change direction and from high magnetization to low magnetization state during high to low (H–L) temperature change direction require several field cycles to stabilize the ΔTad measurement, similar to the accommodation phenomenon in hysteretic materials. In the mixed magnetic state inside the first-order transition, both low and high magnetization portions of the alloy exist and it varies considerably with the induced fields. This original observation emphasizes that it is incorrect to assess the performance of a magnetic refrigeration system through a single measurement, and that achieving a stable, utilizable, adiabatic temperature change requires several field-induced transitions.
{"title":"Magnetic states stabilization in Ni51Mn33.4In15.6 Heusler alloy","authors":"M. Ghahremani, A. Aslani, H. Elbidweihy, L. H. Bennett, E. Torre","doi":"10.1080/23311940.2015.1109019","DOIUrl":"https://doi.org/10.1080/23311940.2015.1109019","url":null,"abstract":"Abstract The rate-independent stabilization of magnetic states with iterations in a Heusler alloy has been studied. The direct measurement of the adiabatic temperature change, ΔTad, of a Ni51Mn33.4In15.6 alloy near the magnetostructural phase transition is presented. The adiabatic temperature change at a given temperature within the temperature range of the magnetostructural transition is history dependent and varies considerably with the iteration count of the field cycle. The data show the transition from the low magnetization state to the high magnetization state during low to high (L–H) temperature change direction and from high magnetization to low magnetization state during high to low (H–L) temperature change direction require several field cycles to stabilize the ΔTad measurement, similar to the accommodation phenomenon in hysteretic materials. In the mixed magnetic state inside the first-order transition, both low and high magnetization portions of the alloy exist and it varies considerably with the induced fields. This original observation emphasizes that it is incorrect to assess the performance of a magnetic refrigeration system through a single measurement, and that achieving a stable, utilizable, adiabatic temperature change requires several field-induced transitions.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1109019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-10-29DOI: 10.1080/23311940.2015.1104200
Devender Singh, Vijeta Tanwar, A. Samantilleke, P. S. Kadyan, I. Singh
Abstract Eu3+ doped MLa2O4 (M = Mg, Ca, Sr) nanophosphors were synthesized by a rapid facile gel combustion route. Luminescence properties of these prepared nanophosphors were analyzed by their excitation and emission spectra. The excitation spectrum consisted of some peaks in the 350–410 nm range due to the f–f transitions. The emission spectra of prepared nanophosphors had transitions of Eu3+ ions i.e. 5D0 → 7F0 (580 nm), 5D0 → 7F1 (594–596 nm), 5D0 → 7F2 (614–618, 628–629 nm), and 5D0 → 7F3 (650–651 nm). The main emission peak was observed at 614–618 nm of 5D0→7F2 transitions of Eu3+ ions. The enhancement in optical properties was observed when materials were reheated at higher temperatures. The nanostructural morphology was confirmed with scanning as well as transmission electron microscopy. The prepared materials were having size in the range of 10–50 nm. X-ray powder diffraction (XRD) technique was used to determine the crystal structure and phase of the prepared phosphor materials. XRD measurements revealed that the crystallinity of MLa2O4 materials increased with increasing the sintering temperature. The prepared materials had bright red emitting optical properties that could be suitably applied in various display devices.
{"title":"Optoelectronic characterization of Eu3+ doped MLa2O4 (M = Sr, Ca, Mg) nanophosphors for display devices","authors":"Devender Singh, Vijeta Tanwar, A. Samantilleke, P. S. Kadyan, I. Singh","doi":"10.1080/23311940.2015.1104200","DOIUrl":"https://doi.org/10.1080/23311940.2015.1104200","url":null,"abstract":"Abstract Eu3+ doped MLa2O4 (M = Mg, Ca, Sr) nanophosphors were synthesized by a rapid facile gel combustion route. Luminescence properties of these prepared nanophosphors were analyzed by their excitation and emission spectra. The excitation spectrum consisted of some peaks in the 350–410 nm range due to the f–f transitions. The emission spectra of prepared nanophosphors had transitions of Eu3+ ions i.e. 5D0 → 7F0 (580 nm), 5D0 → 7F1 (594–596 nm), 5D0 → 7F2 (614–618, 628–629 nm), and 5D0 → 7F3 (650–651 nm). The main emission peak was observed at 614–618 nm of 5D0→7F2 transitions of Eu3+ ions. The enhancement in optical properties was observed when materials were reheated at higher temperatures. The nanostructural morphology was confirmed with scanning as well as transmission electron microscopy. The prepared materials were having size in the range of 10–50 nm. X-ray powder diffraction (XRD) technique was used to determine the crystal structure and phase of the prepared phosphor materials. XRD measurements revealed that the crystallinity of MLa2O4 materials increased with increasing the sintering temperature. The prepared materials had bright red emitting optical properties that could be suitably applied in various display devices.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1104200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-23DOI: 10.1080/23311940.2015.1074146
R. Barlow
New Higgs scalars with masses up to 10 GeV are predicted in models such as the NMSSM, and in scenarios with hidden sectors that couple weakly to the Standard Model. Searches at B factories have resulted in tight constraints on such models. We review the recent searches and new results, and discuss the future outlook for this physics.
{"title":"B-factory searches for light scalars and other new states(i)","authors":"R. Barlow","doi":"10.1080/23311940.2015.1074146","DOIUrl":"https://doi.org/10.1080/23311940.2015.1074146","url":null,"abstract":"New Higgs scalars with masses up to 10 GeV are predicted in models such as the NMSSM, and in scenarios with hidden sectors that couple weakly to the Standard Model. Searches at B factories have resulted in tight constraints on such models. We review the recent searches and new results, and discuss the future outlook for this physics.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1074146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-09-07DOI: 10.1080/23311940.2015.1076702
Nozomu Yasui, M. Sougawa, M. Hirai, K. Yamamoto, T. Okada, D. Yamazaki, Y. Kojima, H. Ohfuji, S. Kunitsugu, K. Takarabe
Abstract Both Re2C and Re2N are ultra incompressible and have a bulk modulus of about 400 GPa. These materials are synthesized under high pressure and high temperature. The synthesis pressures are about 10 GPa or below for Re2C and 20–30 GPa for Re2N. If the synthesis pressure of Re2N was about 10 GPa or below, a large volume high-pressure cell like a multi-anvil apparatus can be used to synthesize Re2N. To realize this, a proper solid nitrogen source is needed instead of liquid or gas nitrogen. We used a precursor of a mixture of rhenium and home-made nanoscale amorphous two-dimensional carbon nitride as a solid nitrogen source. Consequently, the synthesis reaction produced Re2C but not Re2N. We characterized the synthesized Re2C by various techniques including high-pressure x-ray diffraction (XRD). The bulk modulus B0 of the synthesized Re2C under hydrostatic conditions was estimated to be 385.7 ± 18.0 GPa. This value is a little smaller than the previous data. When the pressure medium became non-hydrostatic, the peculiar compression behaviour occurred; the rate of broadening of XRD lines increased and the compression became negligible in the range of a few GPa. The reason for this peculiar behaviour is not known.
{"title":"High-pressure and high-temperature synthesis of rhenium carbide using rhenium and nanoscale amorphous two-dimensional carbon nitride1","authors":"Nozomu Yasui, M. Sougawa, M. Hirai, K. Yamamoto, T. Okada, D. Yamazaki, Y. Kojima, H. Ohfuji, S. Kunitsugu, K. Takarabe","doi":"10.1080/23311940.2015.1076702","DOIUrl":"https://doi.org/10.1080/23311940.2015.1076702","url":null,"abstract":"Abstract Both Re2C and Re2N are ultra incompressible and have a bulk modulus of about 400 GPa. These materials are synthesized under high pressure and high temperature. The synthesis pressures are about 10 GPa or below for Re2C and 20–30 GPa for Re2N. If the synthesis pressure of Re2N was about 10 GPa or below, a large volume high-pressure cell like a multi-anvil apparatus can be used to synthesize Re2N. To realize this, a proper solid nitrogen source is needed instead of liquid or gas nitrogen. We used a precursor of a mixture of rhenium and home-made nanoscale amorphous two-dimensional carbon nitride as a solid nitrogen source. Consequently, the synthesis reaction produced Re2C but not Re2N. We characterized the synthesized Re2C by various techniques including high-pressure x-ray diffraction (XRD). The bulk modulus B0 of the synthesized Re2C under hydrostatic conditions was estimated to be 385.7 ± 18.0 GPa. This value is a little smaller than the previous data. When the pressure medium became non-hydrostatic, the peculiar compression behaviour occurred; the rate of broadening of XRD lines increased and the compression became negligible in the range of a few GPa. The reason for this peculiar behaviour is not known.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1076702","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-08-12DOI: 10.1080/23311940.2015.1070661
Kevin Gooniah, Hanshika Jhurree, L. Rhyman, I. Alswaidan, H. Fun, R. Somanah, P. Ramasami
Abstract Molecular parameters such as equilibrium structure, dipole moment, rotational constant, harmonic frequency, IR intensity, adiabatic electron affinity, atomisation energy and ionisation potential of some P-bearing molecules PS, PO and HC3P in their neutral, cationic and anionic forms were investigated using the popular B3LYP hybrid density functional with four basis sets 6-311++G(2df,2pd), 6-311++G(3df,3pd), cc-pVTZ and aug-cc-pVTZ. The computed data conform well to those existing in the literature. Therefore, the predicted data for those molecules or ions which are not available in the literature should be reliable.
{"title":"Structural, spectroscopic and energetic parameters of P-bearing species having astrophysical importance","authors":"Kevin Gooniah, Hanshika Jhurree, L. Rhyman, I. Alswaidan, H. Fun, R. Somanah, P. Ramasami","doi":"10.1080/23311940.2015.1070661","DOIUrl":"https://doi.org/10.1080/23311940.2015.1070661","url":null,"abstract":"Abstract Molecular parameters such as equilibrium structure, dipole moment, rotational constant, harmonic frequency, IR intensity, adiabatic electron affinity, atomisation energy and ionisation potential of some P-bearing molecules PS, PO and HC3P in their neutral, cationic and anionic forms were investigated using the popular B3LYP hybrid density functional with four basis sets 6-311++G(2df,2pd), 6-311++G(3df,3pd), cc-pVTZ and aug-cc-pVTZ. The computed data conform well to those existing in the literature. Therefore, the predicted data for those molecules or ions which are not available in the literature should be reliable.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1070661","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-17DOI: 10.1080/23311940.2015.1058465
C. Clement
This paper presents the results of several searches for dark matter with the ATLAS experiment at Large Hadron Collider using proton–proton collisions at TeV. These include searches for events with large missing transverse momentum and a photon, a single jet or boson. Both hadronic and leptonic decays are considered. In a number of models, the dark matter particles can be produced in association with heavy flavour (top or b-quarks). Results of these searches are summarised.
{"title":"Search for dark matter with the ATLAS detector","authors":"C. Clement","doi":"10.1080/23311940.2015.1058465","DOIUrl":"https://doi.org/10.1080/23311940.2015.1058465","url":null,"abstract":"This paper presents the results of several searches for dark matter with the ATLAS experiment at Large Hadron Collider using proton–proton collisions at TeV. These include searches for events with large missing transverse momentum and a photon, a single jet or boson. Both hadronic and leptonic decays are considered. In a number of models, the dark matter particles can be produced in association with heavy flavour (top or b-quarks). Results of these searches are summarised.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1058465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-07-17DOI: 10.1080/23311940.2015.1067344
M. Arunachalam, P. Thamilmaran, S. Sankarrajan, K. Sakthipandi
Abstract La1−xNaxMnO3 perovskite manganite in the form of circular pellets was prepared with the composition of x = 0.10, 0.15 and 0.20 by the solid-state reaction technique. To confirm the crystalline nature of the samples, X-ray diffraction patterns of the samples were obtained. It is found that the samples have a rhombohedral structure with R3c space group. Particle size was determined from the obtained scanning electron microscope images. Ultrasonic velocity and the attenuation measurements were carried out on the samples employing the transmission technique in the temperature range from 300 to 400 K. The anomalous behaviour obtained in the ultrasonic measurements was used to explore the transition temperature of the prepared La1−xNaxMnO3 perovskite samples. The temperatures 320, 328 and 334 K are the ferromagnetic to paramagnetic phase transition temperatures of the samples x = 0.10, 0.15 and 0.20, respectively.
{"title":"Ultrasonic studies on sodium-doped LaMnO3 perovskite material","authors":"M. Arunachalam, P. Thamilmaran, S. Sankarrajan, K. Sakthipandi","doi":"10.1080/23311940.2015.1067344","DOIUrl":"https://doi.org/10.1080/23311940.2015.1067344","url":null,"abstract":"Abstract La1−xNaxMnO3 perovskite manganite in the form of circular pellets was prepared with the composition of x = 0.10, 0.15 and 0.20 by the solid-state reaction technique. To confirm the crystalline nature of the samples, X-ray diffraction patterns of the samples were obtained. It is found that the samples have a rhombohedral structure with R3c space group. Particle size was determined from the obtained scanning electron microscope images. Ultrasonic velocity and the attenuation measurements were carried out on the samples employing the transmission technique in the temperature range from 300 to 400 K. The anomalous behaviour obtained in the ultrasonic measurements was used to explore the transition temperature of the prepared La1−xNaxMnO3 perovskite samples. The temperatures 320, 328 and 334 K are the ferromagnetic to paramagnetic phase transition temperatures of the samples x = 0.10, 0.15 and 0.20, respectively.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1067344","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-06-24DOI: 10.1080/23311940.2015.1054679
A. Coccaro
The nature of dark matter (DM) is one of the most intriguing questions in particle physics. DM can be postulated to be part of a hidden sector whose interactions with the visible matter are not completely decoupled. The discovery of a fundamental scalar particle compatible with the Higgs boson predicted by the Standard Model paves the way for looking for DM with novel methods. An overview of the searches looking for a hidden sector in exotic Higgs decays and for invisible decays of the Higgs boson within the ATLAS experiment is presented. Prospects for searches with Large Hadron Collider data at a center-of-mass energy of 13 TeV are summarized.
{"title":"Looking for a hidden sector in exotic Higgs boson decays with the ATLAS experiment","authors":"A. Coccaro","doi":"10.1080/23311940.2015.1054679","DOIUrl":"https://doi.org/10.1080/23311940.2015.1054679","url":null,"abstract":"The nature of dark matter (DM) is one of the most intriguing questions in particle physics. DM can be postulated to be part of a hidden sector whose interactions with the visible matter are not completely decoupled. The discovery of a fundamental scalar particle compatible with the Higgs boson predicted by the Standard Model paves the way for looking for DM with novel methods. An overview of the searches looking for a hidden sector in exotic Higgs decays and for invisible decays of the Higgs boson within the ATLAS experiment is presented. Prospects for searches with Large Hadron Collider data at a center-of-mass energy of 13 TeV are summarized.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1054679","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-06-18DOI: 10.1080/23311940.2015.1049477
G. Ackland, I. Magdău
Molecular dynamics (MD) is a powerful method for studying the behaviour of materials at high temperature. In practice, however, its effectiveness in representing real systems is limited by the accuracy of the forces, finite size effects, quantization and equilibration methods. In this paper, we report and discuss some calculations carried out using MD on high-pressure hydrogen, reviewing a number of sources of error, of which the neglect of zero-point vibrations is quantitatively the largest. We show that simulations using ab initio MD with the PBE functional predict a large stability field for the molecular Cmca4 structure at pressures just above those achieved in current experiments above the stability range of the mixed molecular layered Phase IV. However, the various errors in the simulation all point towards a much smaller stability range, and the likelihood of a non-molecular phase based on low-coordination networks or chains of atoms.
{"title":"Appraisal of the realistic accuracy of molecular dynamics of high-pressure hydrogen","authors":"G. Ackland, I. Magdău","doi":"10.1080/23311940.2015.1049477","DOIUrl":"https://doi.org/10.1080/23311940.2015.1049477","url":null,"abstract":"Molecular dynamics (MD) is a powerful method for studying the behaviour of materials at high temperature. In practice, however, its effectiveness in representing real systems is limited by the accuracy of the forces, finite size effects, quantization and equilibration methods. In this paper, we report and discuss some calculations carried out using MD on high-pressure hydrogen, reviewing a number of sources of error, of which the neglect of zero-point vibrations is quantitatively the largest. We show that simulations using ab initio MD with the PBE functional predict a large stability field for the molecular Cmca4 structure at pressures just above those achieved in current experiments above the stability range of the mixed molecular layered Phase IV. However, the various errors in the simulation all point towards a much smaller stability range, and the likelihood of a non-molecular phase based on low-coordination networks or chains of atoms.","PeriodicalId":43050,"journal":{"name":"Cogent Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23311940.2015.1049477","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60084402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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