News about our Research
Spin-Orbit-Coupling Effects in (Bio)inorganic Complexes Studied with New Algorithm
July 28, 2009
Our research group has implemented an accurate computational methodology for predicting the effects of spin-orbit coupling (SOC), a relativistic effect, on physico-chemical properties of metallo-proteins and (bio)inorganic complexes. In particular, a phenomenon known in the field of molecular magnetism as "zero field splitting" (ZFS), which removes the ground state spin-degeneracy of a system, has been predicted with very good accuracy. Aquino and Rodriguez published a paper [J. Phys. Chem. A, Articles ASAP, July 2009] describing a methodology, based on the combination of spin density functional theory and perturbation theory (SDFT-PT), which is capable of predicting the ZFS of transition metal-containing complexes of relevance in metallo-enzyme biochemistry, inorganic/bioinorganic chemistry, and molecular magnet-based nanotechnology. Their latest paper follows a previous paper on the subject [J. Chem. Phys., Vol. 123, 204902, 2005].
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Professor Jorge Rodriguez Interviewed by Science Magazine
May 17, 2006
Professor Jorge Rodriguez has been interviewed for a special "career development" article sponsored by Science Magazine. In a May 17, 2006 special supplement titled "Chemistry: First Principles-Calculations" the author Mike May features an interview with Prof. Rodriguez and three other experts about new career opportunities for scientists working on first-principles and quantum chemical computational methods. The full article can be found at:
Mechanisms of Molecular Spin-Photoswitches Studied with New Algorithm.
September 8, 2005
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Spin is a quantum property of electrons. Chemists and physicists have long known that many iron-containing molecules often have a "net spin" associated with their outermost electrons. Most often, iron complexes that are excited with light will make a transition from a low energy electronic configuration to a higher energy configuration but will eventually return to their lowest energy state. Chemists and physicists call this lowest energy state the "molecular ground state". The Rodriguez group has been using quantum physics, quantum chemistry, and supercomputers to study a remarkable class of iron complexes which, upon excitation with light, do not return to their spin ground state.
Our research group has developed techniques of computational quantum mechanics to study iron-containing "spin-photoswitches". Contrary to common iron complexes, spin photoswitches can be excited with light but, after making a transition to a higher spin and higher energy state, these do not return to their original ground state. Instead, these remarkable molecular crystals remain in a metastable high spin state as long as their temperature is below some 50 Kelvin. This phenomenom, which has been previously discovered by experimentalists, is called it light-induced excited-state spin trapping "LIESST".
Rodriguez used time-dependent density functional theory in conjunction with supercomputers to elucidate the initial excitations that take place at the onset of the LIESST process [J. Chem. Phys., Vol. 123, 094709, 2005]. In addition, Chachiyo and Rodriguez published a paper [J. Chem. Phys., Vol. 123, 094711, 2005] that describes a computational algorithm to follow the structural rearrangements and changes in spin state during the LIESST process. The computational studies show that there is a sequence of spin states which the photoswitches can go through, forming a pathway which takes them from the ground state to the metastable high spin state. This is a novel description of the mechanism by which iron spin photoswitches work. These theoretical results will likely aid to the development of better quality molecular photoswitches which, by remaining trapped in a metastable spin state at high temperatures, may be used in molecular-level memory storage of liquid display technological applications. Molecular-level memory storage is seen as a powerful futuristic way to store huge amounts of information in very small (nanoscale) regions of space. The work done by the Rodriguez group is an example of how computational quantum physics and quantum inorganic chemistry can contribute to the development of novel nanoscale technological devices.
The research was supported in part by a NSF CAREER award CHE-0349189 (JHR).
FIGURE CAPTION: The iron complex shown in the figure is a spin photoswitch that, upon excitation with green light, can change its spin from S=0 to S=2. The Rodriguez group has used supercomputers, quantum physics, and quantum chemistry to discover novel mechanisms about the spin-photoswitching process.
Prof. Jorge Rodríguez Receives Prestigious NSF CAREER Award.
January 15, 2004
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The National Science Foundation (NSF) has granted a CAREER award to Jorge Rodríguez, Assistant Professor of Physics at Purdue. This award intends to foster Prof. Rodríguez's theoretical and computational research on biomolecular and mesoscopic physics and, in particular, on quantum models of the electronic structure and biological function of magnetically ordered metalloproteins. This award also intends to contribute to Prof. Rodríguez's various educational efforts. According to NSF, the CAREER is its "most prestigious award for new faculty members. The CAREER program recognizes and supports the early career-development activities of those teacher-scholars who are most likely to become the academic leaders of the 21st century." The award carries with it funding for five consecutive years.
The antiferromagnetic spin couplings in structural models for diiron-oxo proteins; have been predicted with unprecedented accuracy.
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September 14, 2002
First principle calculations based on density functional theory(DFT), in conjunction with high performance supercomputers, were carried out to obtain these results. Our computational method is potentially a powerful and novel alternative to susceptibility or other experimental methods which have been traditionally used to determine magnetic parameters. We have reported these results in an extensive publication [J. Chem. Phys. 116, 6253-6270, 2002].