5 Search Results

TURBOMOLE is a highly optimized software suite for large-scale quantum-chemical and materials science simulations of molecules, clusters, extended systems, and periodic solids. TURBOMOLE uses Gaussian basis sets and has been designed with robust and fast quantum-chemical applications in mind, ranging from homogeneous and heterogeneous catalysis to inorganic and organic chemistry and various types of spectroscopy, light–matter interactions, and biochemistry. This Perspective briefly surveys TURBOMOLE’s functionality and highlights recent developments that have taken place between 2020 and 2023, comprising new electronic structure methods for molecules and solids, previously unavailable molecular properties, embedding, and molecular dynamics approaches. Select features under development aremore » reviewed to illustrate the continuous growth of the program suite, including nuclear electronic orbital methods, Hartree–Fock-based adiabatic connection models, simplified time-dependent density functional theory, relativistic effects and magnetic properties, and multiscale modeling of optical properties.« less

TURBOMOLE is a collaborative, multi-national software development project aiming to provide highly efficient and stable computational tools for quantum chemical simulations of molecules, clusters, periodic systems, and solutions. The TURBOMOLE software suite is optimized for widely available, inexpensive, and resource-efficient hardware such as multi-core workstations and small computer clusters. TURBOMOLE specializes in electronic structure methods with outstanding accuracy–cost ratio, such as density functional theory including local hybrids and the random phase approximation (RPA), GW-Bethe–Salpeter methods, second-order Møller–Plesset theory, and explicitly correlated coupled-cluster methods. TURBOMOLE is based on Gaussian basis sets and has been pivotal for the development of many fastmore » and low-scaling algorithms in the past three decades, such as integral-direct methods, fast multipole methods, the resolution-of-the-identity approximation, imaginary frequency integration, Laplace transform, and pair natural orbital methods. This review focuses on recent additions to TURBOMOLE’s functionality, including excited-state methods, RPA and Green’s function methods, relativistic approaches, high-order molecular properties, solvation effects, and periodic systems. A variety of illustrative applications along with accuracy and timing data are discussed. Moreover, available interfaces to users as well as other software are summarized. TURBOMOLE’s current licensing, distribution, and support model are discussed, and an overview of TURBOMOLE’s development workflow is provided. Challenges such as communication and outreach, software infrastructure, and funding are highlighted.« less

Ammonia and amines are emitted into the troposphere by various natural and anthropogenic sources, where they have a significant role in aerosol formation. Here, we explore the significance of their removal by reaction with Criegee intermediates, which are produced in the troposphere by ozonolysis of alkenes. Rate coefficients for the reactions of two representative Criegee intermediates, formaldehyde oxide (CH₂OO) and acetone oxide ((CH₃)₂COO) with NH₃ and CH₃NH₂ were measured using cavity ring-down spectroscopy. Temperature-dependent rate coefficients, k(CH₂OO + NH₃) = (3.1 ± 0.5) × 10^-20T²exp(1011 ± 48/T) cm³ s^-1 and k(CH₂OO + CH₃NH₂) = (5 ± 2) × 10^-19T² exp(1384more » ± 96/T) cm³ s^-1 were obtained in the 240 to 320 K range. Both the reactions of CH₂OO were found to be independent of pressure in the 10 to 100 Torr (N₂) range, and average rate coefficients k(CH₂OO + NH₃) = (8.4 ± 1.2) × 10^-14 cm³ s^-1 and k(CH₂OO + CH₃NH₂) = (5.6 ± 0.4) × 10^-12 cm³ s^-1 were deduced at 293 K. An upper limit of ≤2.7 × 10^-15 cm³ s^-1 was estimated for the rate coefficient of the (CH₃)₂COO + NH3 reaction. Complementary measurements were performed with mass spectrometry using synchrotron radiation photoionization giving k(CH₂OO + CH₃NH₂) = (4.3 ± 0.5) × 10-12 cm3 s-1 at 298 K and 4 Torr (He). Photoionization mass spectra indicated production of NH₂CH₂OOH and CH₃N(H)CH₂OOH functionalized organic hydroperoxide adducts from CH₂OO + NH₃ and CH₂OO + CH₃NH₂ reactions, respectively. Ab initio calculations performed at the CCSD(T)(F12*)/cc-pVQZ-F12//CCSD(T)(F12*)/cc-pVDZ-F12 level of theory predicted pre-reactive complex formation, consistent with previous studies. Master equation simulations of the experimental data using the ab initio computed structures identified submerged barrier heights of -2.1 ± 0.1 kJ mol^-1 and -22.4 ± 0.2 kJ mol^-1 for the CH₂OO + NH₃ and CH₂OO + CH₃NH₂ reactions, respectively. The reactions of NH3 and CH3NH2 with CH₂OO are not expected to compete with its removal by reaction with (H₂O)₂ in the troposphere. Similarly, losses of NH₃ and CH₃NH₂ by reaction with Criegee intermediates will be insignificant compared with reactions with OH radicals.« less

The efficient calculation of Hamiltonian spectra, a problem often intractable on classical machines, can find application in many fields, from physics to chemistry. We introduce the concept of an “eigenstate witness” and, through it, provide a new quantum approach that combines variational methods and phase estimation to approximate eigenvalues for both ground and excited states. This protocol is experimentally verified on a programmable silicon quantum photonic chip, a mass-manufacturable platform, which embeds entangled state generation, arbitrary controlled unitary operations, and projective measurements. Both ground and excited states are experimentally found with fidelities >99%, and their eigenvalues are estimated with 32more » bits of precision. We also investigate and discuss the scalability of the approach and study its performance through numerical simulations of more complex Hamiltonians. This result shows promising progress toward quantum chemistry on quantum computers.« less

Carbenes of platinum and palladium, PtC₃ and PdC₃ , were generated in the gas phase through laser vaporization of a metal target in the presence of a low concentration of a hydrocarbon precursor undergoing supersonic expansion. Rotational spectroscopy and abinitio calculations confirm that both molecules are linear. The geometry of PtC₃ was accurately determined by fitting to the experimental moments of inertia of twenty-six isotopologues. In conclusion, the results are consistent with the proposal of an autogenic isolobal relationship between O, Au⁺ , and Ptatoms.