Project acronym APES
Project Accuracy and precision for molecular solids
Researcher (PI) Jiri KLIMES
Host Institution (HI) UNIVERZITA KARLOVA
Call Details Starting Grant (StG), PE4, ERC-2017-STG
Summary The description of high pressure phases or polymorphism of molecular solids represents a significant scientific challenge both for experiment and theory. Theoretical methods that are currently used struggle to describe the tiny energy differences between different phases. It is the aim of this project to develop a scheme that would allow accurate and reliable predictions of the binding energies of molecular solids and of the energy differences between different phases.
To reach the required accuracy, we will combine the coupled cluster approach, widely used for reference quality calculations for molecules, with the random phase approximation (RPA) within periodic boundary conditions. As I have recently shown, RPA-based approaches are already some of the most accurate and practically usable methods for the description of extended systems. However, reliability is not only a question of accuracy. Reliable data need to be precise, that is, converged with the numerical parameters so that they are reproducible by other researchers.
Reproducibility is already a growing concern in the field. It is likely to become a considerable issue for highly accurate methods as the calculated energies have a stronger dependence on the simulation parameters such as the basis set size. Two main approaches will be explored to assure precision. First, we will develop the so-called asymptotic correction scheme to speed-up the convergence of the correlation energies with the basis set size. Second, we will directly compare the lattice energies from periodic and finite cluster based calculations. Both should yield identical answers, but if and how the agreement can be reached for general system is currently far from being understood for methods such as coupled cluster. Reliable data will allow us to answer some of the open questions regarding the stability of polymorphs and high pressure phases, such as the possibility of existence of high pressure ionic phases of water and ammonia.
Summary
The description of high pressure phases or polymorphism of molecular solids represents a significant scientific challenge both for experiment and theory. Theoretical methods that are currently used struggle to describe the tiny energy differences between different phases. It is the aim of this project to develop a scheme that would allow accurate and reliable predictions of the binding energies of molecular solids and of the energy differences between different phases.
To reach the required accuracy, we will combine the coupled cluster approach, widely used for reference quality calculations for molecules, with the random phase approximation (RPA) within periodic boundary conditions. As I have recently shown, RPA-based approaches are already some of the most accurate and practically usable methods for the description of extended systems. However, reliability is not only a question of accuracy. Reliable data need to be precise, that is, converged with the numerical parameters so that they are reproducible by other researchers.
Reproducibility is already a growing concern in the field. It is likely to become a considerable issue for highly accurate methods as the calculated energies have a stronger dependence on the simulation parameters such as the basis set size. Two main approaches will be explored to assure precision. First, we will develop the so-called asymptotic correction scheme to speed-up the convergence of the correlation energies with the basis set size. Second, we will directly compare the lattice energies from periodic and finite cluster based calculations. Both should yield identical answers, but if and how the agreement can be reached for general system is currently far from being understood for methods such as coupled cluster. Reliable data will allow us to answer some of the open questions regarding the stability of polymorphs and high pressure phases, such as the possibility of existence of high pressure ionic phases of water and ammonia.
Max ERC Funding
924 375 €
Duration
Start date: 2018-01-01, End date: 2022-12-31
Project acronym THz-FRaScan-ESR
Project THz Frequency Rapid Scan – Electron Spin Resonance spectroscopy for spin dynamics investigations of bulk and surface materials (THz-FRaScan-ESR)
Researcher (PI) Petr NEUGEBAUER
Host Institution (HI) VYSOKE UCENI TECHNICKE V BRNE
Call Details Starting Grant (StG), PE4, ERC-2016-STG
Summary Current high frequency electron spin resonance (HFESR) instruments suffer from the disadvantages of being limited to a single frequency and to tiny sample volumes. The study of spin dynamics at frequencies beyond a few hundred gigahertz is currently prohibitively difficult. These limitations are now preventing progress in dynamic nuclear polarization (DNP) and preclude the implementation of zero-field quantum computing. In order to revolutionize sensitivity in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) by means of DNP techniques allowing to watch in real time molecular interactions or even to monitor how sophisticated systems (ribosomes) work, the HFESR methods have to be substantially improved. I will develop a novel and worldwide unique technique called broadband terahertz frequency rapid scan (FRaScan) ESR. I intend to implement this method into a working prototype, which will seamlessly span the entire frequency range from 100 GHz to 1 THz, and allow spin dynamics investigation of large samples. This revolutionary new concept based on rapid frequency sweeps will remove all the restrictions and limitations of conventional HFESR methods used nowadays. It will enable for the first time multi-frequency studies of quantum coherence also in zero magnetic field. It will lead to substantial increases in sensitivity and concurrent decrease of measurement time, thus allowing more efficient use of resources. Finally, the method will allow identification of novel DNP signal enhancement agents, ultimately leading to a step change improvement of the MRI method. It will drastically shorten MRI scan times in hospitals, greatly enhancing patient comfort together with significantly better and precise diagnoses. The method will lead to zero field quantum computers with computation power which will be never reached with conventional technology. In summary it will lead to impacts far beyond the scientific community.
Summary
Current high frequency electron spin resonance (HFESR) instruments suffer from the disadvantages of being limited to a single frequency and to tiny sample volumes. The study of spin dynamics at frequencies beyond a few hundred gigahertz is currently prohibitively difficult. These limitations are now preventing progress in dynamic nuclear polarization (DNP) and preclude the implementation of zero-field quantum computing. In order to revolutionize sensitivity in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) by means of DNP techniques allowing to watch in real time molecular interactions or even to monitor how sophisticated systems (ribosomes) work, the HFESR methods have to be substantially improved. I will develop a novel and worldwide unique technique called broadband terahertz frequency rapid scan (FRaScan) ESR. I intend to implement this method into a working prototype, which will seamlessly span the entire frequency range from 100 GHz to 1 THz, and allow spin dynamics investigation of large samples. This revolutionary new concept based on rapid frequency sweeps will remove all the restrictions and limitations of conventional HFESR methods used nowadays. It will enable for the first time multi-frequency studies of quantum coherence also in zero magnetic field. It will lead to substantial increases in sensitivity and concurrent decrease of measurement time, thus allowing more efficient use of resources. Finally, the method will allow identification of novel DNP signal enhancement agents, ultimately leading to a step change improvement of the MRI method. It will drastically shorten MRI scan times in hospitals, greatly enhancing patient comfort together with significantly better and precise diagnoses. The method will lead to zero field quantum computers with computation power which will be never reached with conventional technology. In summary it will lead to impacts far beyond the scientific community.
Max ERC Funding
1 999 874 €
Duration
Start date: 2018-01-01, End date: 2022-12-31
Project acronym TSuNAMI
Project Trans-Spin NanoArchitectures: from birth to functionalities in magnetic field
Researcher (PI) Jana KALBACOVA VEJPRAVOVA
Host Institution (HI) UNIVERZITA KARLOVA
Call Details Starting Grant (StG), PE4, ERC-2016-STG
Summary Control over electrons in molecules and periodic solids can be reached via manipulation of their internal quantum degrees of freedom. The most prominent and exploited case is the electronic spin accommodated in standalone spin units composed of 1 – 10^5 of spins. A challenging alternative to the spin is the binary quantum degree of freedom, termed pseudospin existing e.g. in two-dimensional semiconductors. The aim of the proposed research is to build prototypes of trans-spin nano-architectures composed of at least two divergent spin entities, the TSuNAMIes. The spin entities of interest correspond to single atomic spin embedded in spin crossover complexes (SCO), molecular spin of molecular magnets (SMM), superspins of single-domain magnetic nanoparticles (SuperS) and pseudospins in two-dimensional transition metal dichalcogenides (PseudoS). Ultimate goal of the project is to identify a profit from trans-spin cooperation between the different spin entities coexisting in a single TSuNAMI. Influence of external static and alternating magnetic fields on the elementary spin state, unit cell magnetic structure, long-range magnetic order, mesoscopic spin order, spin relaxations and pseudospin state mirrored in essential fingerprints of the spin units and their ensembles will be explored using macroscopic and microscopic in situ and ex situ probes, including Raman and Mössbauer spectroscopies in magnetic field. Within the proposed high-risk/high-gain trans-spin strategy, we thus expect: 1. Enhancement of magnetic anisotropy in SMM-SuperS with enormous impact on cancer therapy using magnetic fluid hyperthermia, 2. Control over SCO via coupling to giant classical spin giving rise to miniature ‘on-particle’ sensors, 3. Mutual visualization of electronic states in SCO-PseudoS pushing frontiers of nowadays pseudospintronics, and 4. Control over electronic states with nanometer resolution in SuperS-PseudoS giving rise to novel functionalization strategies of graphene successor.
Summary
Control over electrons in molecules and periodic solids can be reached via manipulation of their internal quantum degrees of freedom. The most prominent and exploited case is the electronic spin accommodated in standalone spin units composed of 1 – 10^5 of spins. A challenging alternative to the spin is the binary quantum degree of freedom, termed pseudospin existing e.g. in two-dimensional semiconductors. The aim of the proposed research is to build prototypes of trans-spin nano-architectures composed of at least two divergent spin entities, the TSuNAMIes. The spin entities of interest correspond to single atomic spin embedded in spin crossover complexes (SCO), molecular spin of molecular magnets (SMM), superspins of single-domain magnetic nanoparticles (SuperS) and pseudospins in two-dimensional transition metal dichalcogenides (PseudoS). Ultimate goal of the project is to identify a profit from trans-spin cooperation between the different spin entities coexisting in a single TSuNAMI. Influence of external static and alternating magnetic fields on the elementary spin state, unit cell magnetic structure, long-range magnetic order, mesoscopic spin order, spin relaxations and pseudospin state mirrored in essential fingerprints of the spin units and their ensembles will be explored using macroscopic and microscopic in situ and ex situ probes, including Raman and Mössbauer spectroscopies in magnetic field. Within the proposed high-risk/high-gain trans-spin strategy, we thus expect: 1. Enhancement of magnetic anisotropy in SMM-SuperS with enormous impact on cancer therapy using magnetic fluid hyperthermia, 2. Control over SCO via coupling to giant classical spin giving rise to miniature ‘on-particle’ sensors, 3. Mutual visualization of electronic states in SCO-PseudoS pushing frontiers of nowadays pseudospintronics, and 4. Control over electronic states with nanometer resolution in SuperS-PseudoS giving rise to novel functionalization strategies of graphene successor.
Max ERC Funding
1 500 000 €
Duration
Start date: 2017-02-01, End date: 2022-01-31
