The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Andreas M. Köster - One of the best experts on this subject based on the ideXlab platform.
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mixed second and third energy derivatives from Auxiliary Density perturbation theory
Molecular Physics, 2019Co-Authors: Rogelio Isaac Delgadovenegas, Patrizia Calaminici, Andreas M. KösterAbstract:AbstractThe working equations for the calculation of mixed second- and third-order energy derivatives in the framework of Auxiliary Density functional theory are presented. The perturbations with r...
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Accuracy of Auxiliary Density functional theory hybrid calculations for activation and reaction enthalpies of pericyclic reactions
Journal of Molecular Modeling, 2018Co-Authors: José R. Gómez-pérez, Patrizia Calaminici, Francisco A. Delesma, Andreas M. KösterAbstract:Auxiliary Density functional theory (ADFT) hybrid calculations are based on the variational fitting of the Coulomb and Fock potential and, therefore, are free of four-center electron repulsion integrals. So far, ADFT hybrid calculations have been validated successfully for standard enthalpies of formation. In this work the accuracy of ADFT hybrid calculations for the description of pericyclic reactions was quantitatively validated at the B3LYP/6-31G*/GEN-A2* level of theory. Our comparison with conventional Kohn-Sham Density functional theory (DFT) results shows that the DFT and ADFT activation and reaction enthalpies are practically indistinguishable. A systematic study of various functionals (PBE, B3LYP, PBE0, CAMB3LYP, CAMPBE0 and HSE06) and basis sets (6-31G*, DZVP-GGA and aug-cc-pVXZ; X = D, T and Q) revealed that the ADFT HSE06/aug-cc-pVTZ/GEN-A2* level of theory yields best balanced accuracy for the activation and reaction enthalpies of the studied pericyclic reactions. With the successfully validate ADFT composite approach consisting of PBE/DZVP-GGA/GEN-A2* structure and transition state optimizations and single-point HSE06/aug-cc-pVTZ/GEN-A2* energy calculations, an accurate, reliable and efficient computational approach for the study of pericyclic reactions in systems at the nanometer scale is proposed.
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The melting limit in sodium clusters
Theoretical Chemistry Accounts, 2018Co-Authors: José Manuel Vásquez-pérez, Andreas M. Köster, Patrizia CalaminiciAbstract:Thermodynamic properties of the small sodium clusters $$\hbox {Na}_6,\, \hbox {Na}_8$$ Na 6 , Na 8 and $$\hbox {Na}_{10}$$ Na 10 have been studied by Born–Oppenheimer molecular dynamics (BOMD) simulations. The simulations were performed with Auxiliary Density functional theory as implemented in the deMon2k code. This approach has already proved accurate for the calculations of thermodynamic properties of larger sodium clusters. The Nosé–Hoover chain thermostat was applied to control the temperature. BOMD simulations were performed in the temperature range from 250 to 1000 K. The obtained trajectories were analyzed using the multiple-histogram method in order to obtain continuous functions for the energies and heat capacities. For the $$\hbox {Na}_6$$ Na 6 and $$\hbox {Na}_8$$ Na 8 clusters, besides the fragmentation of the clusters at higher temperature, no other characteristic features in the heat capacity curves are found. On the other hand, a small peak at low temperature was found in the $$\hbox {Na}_{10}$$ Na 10 heat capacity curve which is characteristic for molecular melting. Our analysis of the $$\hbox {Na}_{10}$$ Na 10 melting shows that electronic structure parameters are better suited than geometrical ones to describe the melting process due to the fluctional nature of the clusters. We find that energetical resorting of the occupied cluster orbitals is characteristic for the $$\hbox {Na}_{10}$$ Na 10 cluster melting.
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The melting limit in sodium clusters
Theoretical Chemistry Accounts, 2018Co-Authors: José Manuel Vásquez-pérez, Andreas M. Köster, Patrizia CalaminiciAbstract:Thermodynamic properties of the small sodium clusters \(\hbox {Na}_6,\, \hbox {Na}_8\) and \(\hbox {Na}_{10}\) have been studied by Born–Oppenheimer molecular dynamics (BOMD) simulations. The simulations were performed with Auxiliary Density functional theory as implemented in the deMon2k code. This approach has already proved accurate for the calculations of thermodynamic properties of larger sodium clusters. The Nose–Hoover chain thermostat was applied to control the temperature. BOMD simulations were performed in the temperature range from 250 to 1000 K. The obtained trajectories were analyzed using the multiple-histogram method in order to obtain continuous functions for the energies and heat capacities. For the \(\hbox {Na}_6\) and \(\hbox {Na}_8\) clusters, besides the fragmentation of the clusters at higher temperature, no other characteristic features in the heat capacity curves are found. On the other hand, a small peak at low temperature was found in the \(\hbox {Na}_{10}\) heat capacity curve which is characteristic for molecular melting. Our analysis of the \(\hbox {Na}_{10}\) melting shows that electronic structure parameters are better suited than geometrical ones to describe the melting process due to the fluctional nature of the clusters. We find that energetical resorting of the occupied cluster orbitals is characteristic for the \(\hbox {Na}_{10}\) cluster melting.
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Development of Barostats for Finite Systems Born-Oppenheimer Molecular Dynamics Simulations
Revista de la Sociedad Química de Mexico, 2017Co-Authors: Gabriel U. Gamboa, Patrizia Calaminici, Andreas M. KösterAbstract:A new method for pressure control in first-principle molecu- lar dynamics simulations for finite systems is presented. The extended Lagrangian methodology is applied to generate the equations of mo- tion and the system's volume is obtained by a purely geometrical procedure, which is inexpensive in terms of computational cost. The implementation of all discussed algorithms was carried out in the program deMon2k where a robust machinery for Auxiliary Density functional theory calculations exists. The here described methodology extend our effort on property calculations beyond the polyatomic ideal gas approximation on the basis of first-principle electronic structure calculations.
Patrizia Calaminici - One of the best experts on this subject based on the ideXlab platform.
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On the structural, energetic, and magnetic properties of M@Pd (M = Co, Ni, and Cu) core-shell nanoclusters and their comparison with pure Pd nanoclusters
Journal of Magnetism and Magnetic Materials, 2020Co-Authors: H. Cruz-martínez, Patrizia Calaminici, Omar Solorza-feria, D.i. MedinaAbstract:Abstract Electronic structure computations of pure Pd and Pd-based core–shell clusters were studied employing Auxiliary Density functional theory (ADFT). For this investigation icosahedral clusters with 13 and 55 atoms and octahedral clusters with 19 and 44 atoms were employed to analyze the change in the properties of the Pd and M@Pd core–shell clusters. All properties calculated for the M@Pd clusters are directly compared with the ones of pure palladium clusters. Spin multiplicities, spin magnetic moments, spin densities, binding energies per atom, segregation energies, and average bond lengths were calculated to understand their changes when varying the size, composition and shape of the M@Pd (M = Co, Ni, and Cu) core–shell clusters. The M1@Pd12 and M1@Pd18 (M = Co and Cu) clusters exhibit changes in the spin multiplicity and spin magnetic moment with respect to the Pd13 and Pd19 clusters, respectively, whereas the Ni1@Pd12 and Ni1@Pd18 clusters maintain the same properties as their pure Pd counterparts. The spin multiplicities and spin magnetic moments of the M6@Pd38 and M13@Pd42 (M = Co, Ni, and Cu) clusters greatly differ from their pure Pd counterparts. This study reveals that the Pd-Pd bond lengths are shorter in the M@Pd core–shell clusters compared to the ones of pure Pd clusters. This work demonstrates that the binding energy per atom of the M@Pd core–shell clusters is greater than the binding energy per atom of the pure Pd clusters. The calculated segregation energies indicate that 3d atoms prefer to be in the center of core–shell systems.
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Catalytic activity trends from pure Pd nanoclusters to M@PdPt (M = Co, Ni, and Cu) core-shell nanoclusters for the oxygen reduction reaction: A first-principles analysis
International Journal of Hydrogen Energy, 2020Co-Authors: H. Cruz-martínez, Patrizia Calaminici, Omar Solorza-feria, M.m. Tellez-cruz, D.i. MedinaAbstract:Abstract The trends of the catalytic activity toward the oxygen reaction reduction (ORR) from Pd44 nanoclusters to M6@Pd30Pt8 (M = Co, Ni, and Cu) core-shell nanoclusters was investigated using Auxiliary Density functional theory. The adsorption energies of O and OH were computed as predictors of the catalytic activity toward the ORR and the following tendency of the electrocatalytic activity was computed: Pt44 ≈ M6@Pd30Pt8 > M6@Pd38 > Pd44. In addition, the adsorption of O2 on the Ni6@Pd30Pt8 and Pt44 nanoclusters were investigated, finding an elongation of the O–O bond length when O2 is adsorbed on the Ni6@Pd30Pt8 and Pt44 nanoclusters, suggesting that the O2 is activated. Finally, the stabilities of the M6@Pd38 and M6@Pd30Pt8 core-shell nanoclusters were analyzed both in vacuum and in oxidative environment. From the calculated segregation energies for the bimetallic and trimetallic nanoclusters in vacuum, it can be clearly observed that the M atoms prefer to be in the center of the M6@Pd38 and M6@Pd30Pt8 nanoclusters. Nevertheless, it is observed that the segregation energies of M atoms for the M6@Pd38 nanoclusters with an oxidizing environment tend to decrease compared with their M6@Pd38 nanoclusters counterparts in vacuum, which suggests that in an oxidative environment, M atoms may tend to segregate to the surface of the M6@Pd38 nanoclusters.
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mixed second and third energy derivatives from Auxiliary Density perturbation theory
Molecular Physics, 2019Co-Authors: Rogelio Isaac Delgadovenegas, Patrizia Calaminici, Andreas M. KösterAbstract:AbstractThe working equations for the calculation of mixed second- and third-order energy derivatives in the framework of Auxiliary Density functional theory are presented. The perturbations with r...
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Accuracy of Auxiliary Density functional theory hybrid calculations for activation and reaction enthalpies of pericyclic reactions
Journal of Molecular Modeling, 2018Co-Authors: José R. Gómez-pérez, Patrizia Calaminici, Francisco A. Delesma, Andreas M. KösterAbstract:Auxiliary Density functional theory (ADFT) hybrid calculations are based on the variational fitting of the Coulomb and Fock potential and, therefore, are free of four-center electron repulsion integrals. So far, ADFT hybrid calculations have been validated successfully for standard enthalpies of formation. In this work the accuracy of ADFT hybrid calculations for the description of pericyclic reactions was quantitatively validated at the B3LYP/6-31G*/GEN-A2* level of theory. Our comparison with conventional Kohn-Sham Density functional theory (DFT) results shows that the DFT and ADFT activation and reaction enthalpies are practically indistinguishable. A systematic study of various functionals (PBE, B3LYP, PBE0, CAMB3LYP, CAMPBE0 and HSE06) and basis sets (6-31G*, DZVP-GGA and aug-cc-pVXZ; X = D, T and Q) revealed that the ADFT HSE06/aug-cc-pVTZ/GEN-A2* level of theory yields best balanced accuracy for the activation and reaction enthalpies of the studied pericyclic reactions. With the successfully validate ADFT composite approach consisting of PBE/DZVP-GGA/GEN-A2* structure and transition state optimizations and single-point HSE06/aug-cc-pVTZ/GEN-A2* energy calculations, an accurate, reliable and efficient computational approach for the study of pericyclic reactions in systems at the nanometer scale is proposed.
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The melting limit in sodium clusters
Theoretical Chemistry Accounts, 2018Co-Authors: José Manuel Vásquez-pérez, Andreas M. Köster, Patrizia CalaminiciAbstract:Thermodynamic properties of the small sodium clusters $$\hbox {Na}_6,\, \hbox {Na}_8$$ Na 6 , Na 8 and $$\hbox {Na}_{10}$$ Na 10 have been studied by Born–Oppenheimer molecular dynamics (BOMD) simulations. The simulations were performed with Auxiliary Density functional theory as implemented in the deMon2k code. This approach has already proved accurate for the calculations of thermodynamic properties of larger sodium clusters. The Nosé–Hoover chain thermostat was applied to control the temperature. BOMD simulations were performed in the temperature range from 250 to 1000 K. The obtained trajectories were analyzed using the multiple-histogram method in order to obtain continuous functions for the energies and heat capacities. For the $$\hbox {Na}_6$$ Na 6 and $$\hbox {Na}_8$$ Na 8 clusters, besides the fragmentation of the clusters at higher temperature, no other characteristic features in the heat capacity curves are found. On the other hand, a small peak at low temperature was found in the $$\hbox {Na}_{10}$$ Na 10 heat capacity curve which is characteristic for molecular melting. Our analysis of the $$\hbox {Na}_{10}$$ Na 10 melting shows that electronic structure parameters are better suited than geometrical ones to describe the melting process due to the fluctional nature of the clusters. We find that energetical resorting of the occupied cluster orbitals is characteristic for the $$\hbox {Na}_{10}$$ Na 10 cluster melting.
Gerald Geudtner - One of the best experts on this subject based on the ideXlab platform.
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Molecular graphs of $$\hbox {Mo}_{2n}\hbox {C}_n$$ Mo
Theoretical Chemistry Accounts, 2016Co-Authors: Domingo Cruz-olvera, Gerald Geudtner, Patrizia CalaminiciAbstract:The analysis of the molecular graphs of the electron Density $$(\rho )$$ ( ρ ) and the molecular electrostatic potential for molybdenum carbide clusters $$\hbox {Mo}_{2n}\hbox {C}_n$$ Mo 2 n C n with n = 1–10 is presented. For the underlying topological analysis, calculations were performed within the framework of Kohn–Sham Auxiliary Density functional theory employing the linear combination of Gaussian-type orbitals Auxiliary Density functional theory approach. The study was performed considering the ground-state structures of each cluster. Molecular graphs of the Density as well as the molecular electrostatic potential are reported. The differences in the topology of the electron Density and of the molecular electrostatic potential as well as the corresponding molecular graphs of the studied clusters are discussed. This study confirms that C–C bonds are formed for cluster sizes characterized by n = 3, 5 and 6 and provides information about the nature of these bonds.
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Molecular graphs of \hbox {Mo}_{2n}\hbox {C}_n (n = 1–10) clusters
Theoretical Chemistry Accounts, 2016Co-Authors: Domingo Cruz-olvera, Gerald Geudtner, Patrizia CalaminiciAbstract:The analysis of the molecular graphs of the electron Density \((\rho )\) and the molecular electrostatic potential for molybdenum carbide clusters \(\hbox {Mo}_{2n}\hbox {C}_n\) with n = 1–10 is presented. For the underlying topological analysis, calculations were performed within the framework of Kohn–Sham Auxiliary Density functional theory employing the linear combination of Gaussian-type orbitals Auxiliary Density functional theory approach. The study was performed considering the ground-state structures of each cluster. Molecular graphs of the Density as well as the molecular electrostatic potential are reported. The differences in the topology of the electron Density and of the molecular electrostatic potential as well as the corresponding molecular graphs of the studied clusters are discussed. This study confirms that C–C bonds are formed for cluster sizes characterized by n = 3, 5 and 6 and provides information about the nature of these bonds.
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magnetizability tensors from Auxiliary Density functional theory
Journal of Chemical Physics, 2012Co-Authors: Bernardo Zunigagutierrez, Gerald Geudtner, Andreas M. KösterAbstract:The working equations for the calculation of the magnetizability tensor in the framework of Auxiliary Density functional theory with gauge including atomic orbitals (ADFT-GIAO) are derived. Unlike in the corresponding conventional Density functional theory implementations the numerical integration of the GIAOs is avoided in ADFT-GIAO. Our validation shows that this simplification has no effect on the accuracy of the methodology. As a result, a reliable and efficient implementation for the calculation of magnetizabilities of systems with more than 1000 atoms and 14 000 basis functions is presented.
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deMon2k
Wiley Interdisciplinary Reviews: Computational Molecular Science, 2012Co-Authors: Gerald Geudtner, Annick Goursot, Andreas M. Köster, Patrizia Calaminici, Javier Carmona-espíndola, J. M. Del Campo, Victor Daniel Dominguez-soria, R. F. Moreno, Gabriel Ulises Gamboa, Ulises RevelesAbstract:This article provides a brief overview of the quantum chemical Auxiliary Density functional theory program deMon2k. A basic introduction into its key computational features is given. By selected examples, it is shown how deMon2k can contribute to the elucidation of problems in chemistry, biology, and materials science such as finite temperature effects, nuclear magnetic resonance studies, structure determinations, heterogeneous, and enzymatic catalysis
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Static and dynamic polarizability of C540 fullerene
International Journal of Quantum Chemistry, 2012Co-Authors: Patrizia Calaminici, Javier Carmona-espíndola, Gerald Geudtner, Andreas M. KösterAbstract:State-of-the-art calculations of static and dynamic polarizabilities of the giant fullerene C540 are presented. These Density functional theory calculations have been performed using time-dependent Auxiliary Density perturbation theory which was recently implemented in deMon2k (Carmona-Espindola et al., JCP 2010, 133, 084102). For the polarizability calculations the local Density approximation was used in combination with all-electron double-zeta valence polarization basis sets. To gain insight into the trend of these properties as the fullerene size increases the obtained results for C540 are discussed with respect to those obtained for smaller fullerenes such as C60, C70, C180, and C240. All fullerene structures were fully optimized without symmetry constrains. As the cluster size increases the dynamic polarizability strongly increases with respect to the static polarizability. Our analysis shows that static and dynamic polarizabilities per atom increase significantly with fullerene size. Moreover, the increase in the dynamic polarizabilities per atom is larger than for the static ones. © 2012 Wiley Periodicals, Inc.
Roberto Floresmoreno - One of the best experts on this subject based on the ideXlab platform.
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calculation of the epr g tensor from Auxiliary Density functional theory
Journal of Chemical Physics, 2020Co-Authors: Bernardo Zunigagutierrez, Victor Medeljuarez, Andres Varona, Henry Nicole Gonzalez Ramirez, Roberto FloresmorenoAbstract:: The working equations for the calculation of the electron paramagnetic resonance (EPR) g-tensor within the framework of the Auxiliary Density functional theory (ADFT) are presented. The scheme known as gauge including atomic orbitals (GIAOs) is employed to treat the gauge origin problem. This ADFT-GIAO formulation possesses an inherent high computational performance, allowing for the calculation of the EPR g-tensor of molecules containing some hundreds of atoms in reasonable computational time employing moderate computational resources. The effect of the use of a gauge independent Auxiliary Density on the quality of the g-tensor calculation for the evaluation of the exchange-correlation contribution is analyzed in this work. The best agreement with the experiment is obtained with the BLYP functional (Becke 1988 exchange and Lee-Yang-Parr correlation) in combination with a double-ζ basis set, in particular aug-cc-pVDZ. Furthermore, models of endohedral fullerenes N@Cn, with n = {60, 70, 100, 180, 240}, were used for benchmarking its computational performance.
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Auxiliary Density perturbation theory for restricted open shell systems
Revista de la Sociedad Química de Mexico, 2017Co-Authors: Gregorio Guzmanramirez, Francisco J Tenorio, J G Rodriguezzavala, Roberto FloresmorenoAbstract:The recently developed approach to Auxiliary Density per- turbation theory (J. Chem. Phys. 2008, 128, 134105) for the purpose of calculating molecular properties is here extended to include open-shell systems. Both unrestricted and restricted formalisms are considered. A linear equation system, twice as large as the Auxiliary function set is obtained in both cases. For the first time, the formulation for aux- iliary Density perturbation theory for restricted open-shell formalism is derived.
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analytic second derivatives from Auxiliary Density perturbation theory
Journal of Chemical Physics, 2016Co-Authors: Rogelio Isaac Delgadovenegas, Roberto Floresmoreno, Patrizia Calaminici, Daniel Mejiarodriguez, Andreas M. KösterAbstract:The working equations for the calculation of analytic second energy derivatives in the framework of Auxiliary Density functional theory (ADFT) are presented. The needed perturbations are calculated with Auxiliary Density perturbation theory (ADPT) which is extended to perturbation dependent basis and Auxiliary functions sets. The obtained ADPT equation systems are solved with the Eirola-Nevanlinna algorithm. The newly developed analytic second ADFT energy derivative approach was implemented in deMon2k and validated with respect to the corresponding finite difference approach by calculating the harmonic frequencies of small molecules. Good agreement between these two methodologies is found. To analyze the scaling of the new analytic second ADFT energy derivatives with respect to the number of processors in parallel runs, the harmonic frequencies of the carbon fullerene C240 are calculated with varying numbers of processors. Fair scaling up to 720 processors was found. As showcase applications, symmetry unrestricted optimization and frequency analyses of icosahedral carbon fullerenes with up to 960 atoms are presented.
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static and dynamic first hyperpolarizabilities from time dependent Auxiliary Density perturbation theory
International Journal of Quantum Chemistry, 2012Co-Authors: Javier Carmonaespindola, Roberto Floresmoreno, Andreas M. KösterAbstract:A new approach for the calculation of static and dynamic hyperpolarizabilities in the framework of Auxiliary Density perturbation theory is derived. It takes advantage of the Wigner's 2n+1 rule. As a byproduct dynamic quadratic response equations are obtained. Even though the final equations are similar to other approaches they present subtle differences due to their rooting in Auxiliary Density functional theory. The numerical stability and accuracy of the new approach is validated with respect to other theoretical and experimental results. © 2012 Wiley Periodicals, Inc.
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time dependent Auxiliary Density perturbation theory
Journal of Chemical Physics, 2010Co-Authors: Javier Carmonaespindola, Roberto Floresmoreno, Andreas M. KösterAbstract:The recently developed Auxiliary Density perturbation theory is extended to time-dependent perturbations. As its static counterpart, it is based on Auxiliary Density functional theory in which the Coulomb and exchange-correlation potentials are expressed through one Auxiliary function Density. As in the case of static perturbations a noniterative alternative to the corresponding coupled perturbed Kohn–Sham method is formulated. The new methodology is validated by local and gradient corrected dynamical polarizability calculations. Comparison with experiment indicates that for low frequencies reliable dynamical polarizabilities are obtained. Our discussion also shows that the computational performance of time-dependent Auxiliary Density perturbation theory is similar to the previously described static approach. In order to demonstrate the potential of this new methodology, dynamic polarizabilities of C60, C180, and C240 are calculated.
Bernardo Zunigagutierrez - One of the best experts on this subject based on the ideXlab platform.
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calculation of the epr g tensor from Auxiliary Density functional theory
Journal of Chemical Physics, 2020Co-Authors: Bernardo Zunigagutierrez, Victor Medeljuarez, Andres Varona, Henry Nicole Gonzalez Ramirez, Roberto FloresmorenoAbstract:: The working equations for the calculation of the electron paramagnetic resonance (EPR) g-tensor within the framework of the Auxiliary Density functional theory (ADFT) are presented. The scheme known as gauge including atomic orbitals (GIAOs) is employed to treat the gauge origin problem. This ADFT-GIAO formulation possesses an inherent high computational performance, allowing for the calculation of the EPR g-tensor of molecules containing some hundreds of atoms in reasonable computational time employing moderate computational resources. The effect of the use of a gauge independent Auxiliary Density on the quality of the g-tensor calculation for the evaluation of the exchange-correlation contribution is analyzed in this work. The best agreement with the experiment is obtained with the BLYP functional (Becke 1988 exchange and Lee-Yang-Parr correlation) in combination with a double-ζ basis set, in particular aug-cc-pVDZ. Furthermore, models of endohedral fullerenes N@Cn, with n = {60, 70, 100, 180, 240}, were used for benchmarking its computational performance.
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analytical gga exchange correlation kernel calculation in Auxiliary Density functional theory
Molecular Physics, 2016Co-Authors: Bernardo Zunigagutierrez, Andreas M. KösterAbstract:ABSTRACTThe general working equations for the analytical calculation of the kernel of gradient corrected functionals within Auxiliary Density functional theory (ADFT) are presented. This formulation improves even further the computational performance for the calculation of second-order energy derivatives already achieved within the ADFT framework. To show this, we present benchmark polarisability calculations of alkane chains and fullerenes. As a specific example, for a gradient corrected functional, the PW86-P86 functional was used. In comparison to finite-difference kernel calculations, we observe speed-ups of at least a factor of 2 with the new analytical kernel evaluation. The here presented implementation will be of particular importance for indirect spin–spin coupling constant and vibrational frequency calculations in the framework of ADFT.
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efficient calculation of the rotational g tensor from Auxiliary Density functional theory
Journal of Physical Chemistry A, 2015Co-Authors: Bernardo Zunigagutierrez, Patrizia Calaminici, Monica Camachogonzalez, Patricia Simonbastida, Alfonso Bendanacastillo, Andreas M. KösterAbstract:: The computation of the rotational g tensor with the recently developed Auxiliary Density functional theory (ADFT) gauge including atomic orbital (GIAO) methodology is presented. For the rotational g tensor, the calculation of the magnetizability tensor represents the most demanding computational task. With the ADFT-GIAO methodology, the CPU time for the magnetizability tensor calculation can be dramatically reduced. Therefore, it seems most desirable to employ the ADFT-GIAO methodology also for the computation of the rotational g tensor. In this work, the quality of rotational g tensors obtained with the ADFT-GIAO methodology is compared with available experimental data as well as with other theoretical results at the Hartree-Fock and coupled-cluster level of theory. It is found that the agreement between the ADFT-GIAO results and the experiment is good. Furthermore, we also show that the ADFT-GIAO g tensor calculation is applicable to large systems like carbon nanotube models containing hundreds of atom and thousands of basis functions.
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magnetizability tensors from Auxiliary Density functional theory
Journal of Chemical Physics, 2012Co-Authors: Bernardo Zunigagutierrez, Gerald Geudtner, Andreas M. KösterAbstract:The working equations for the calculation of the magnetizability tensor in the framework of Auxiliary Density functional theory with gauge including atomic orbitals (ADFT-GIAO) are derived. Unlike in the corresponding conventional Density functional theory implementations the numerical integration of the GIAOs is avoided in ADFT-GIAO. Our validation shows that this simplification has no effect on the accuracy of the methodology. As a result, a reliable and efficient implementation for the calculation of magnetizabilities of systems with more than 1000 atoms and 14 000 basis functions is presented.
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nmr shielding tensors from Auxiliary Density functional theory
Journal of Chemical Physics, 2011Co-Authors: Bernardo Zunigagutierrez, Gerald Geudtner, Andreas M. KösterAbstract:The working equations for the calculation of NMR shielding tensors in the framework of Auxiliary Density functional theory are derived. It is shown that in this approach the numerical integration over gauge-including atomic orbitals can be avoided without the loss of accuracy. New integral recurrence relations for the required analytic electric-field-type integrals are derived. The computational performance of the resulting formalism permits shielding tensor calculations of systems with more than 1000 atoms and 15 000 basis functions.
