Eva Perlt

Friedrich Schiller University Jena | FSU · Otto Schott Institute of Materials Research (OSIM)

Anharmonic effects play a crucial role in determining thermochemical properties of liquids and gases. For such extended phases, the inclusion of anharmonicity in reliable electronic structure methods is computationally extremely demanding, and hence, anharmonic effects are often lacking in thermochemical calculations. In this study, we apply the qu...

With more and more accurate electronic structure methods at hand, the inclusion of anharmonic effects in the post-processing of such data towards thermochemical properties is the next step. In this...

Brønsted acidity is investigated from a new perspective by using nuclear electronic orbital methods. The orbital energies of the proton wavefunction are related to acid strength in analogy to the Koopmans' theorem for electrons.

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...

This special collection presents original research articles and reviews that are connected to the multifaceted and rich chemistry of water. These works serve as an illustration of how, despite its apparent simplicity and ubiquity, water continues to be at the center of scientific exploration from a wide range of perspectives and employing the toolb...

Time-dependent density functional theory is the method of choice to efficiently calculate excitation spectra with the functional and basis set choice allowing one to compromise between accuracy and computational cost. In this work, the performance of different functionals as well as the second-order approximate coupled cluster singles and doubles m...

Time-dependent density functional theory is the method of choice to efficiently calculate excitation spectra with the functional and basis set choice allowing to compromise between accuracy and computational cost. In this work the performance of different functionals as well as the second-order approximate coupled cluster singles and doubles model...

The theoretical description of water properties continues to be a challenge. Using quantum cluster equilibrium (QCE) theory, we combine state-of-the-art quantum chemistry and statistical thermodynamic methods with the almost historical Clausius–Clapeyron relation to study water self-dissociation and the thermodynamics of vaporization. We pay partic...

The scaling behavior of ab initio molecular dynamics simulations for the different size bulk systems of liquid methanol is presented and thereby the characteristics of every system performing on either a local compute cluster or a supercomputer are analyzed. Additionally, the influence of different parameters on the quality of the infrared and Rama...

The scaling behavior of ab initio molecular dynamics simulations for the different size bulk systems of liquid methanol is presented and thereby the characteristics of every system performing on either a local compute cluster or a supercomputer are analyzed. Additionally, the influence of different parameters on the quality of the infrared and Rama...

We report the synthesis and characterization of the trinuclear 4d-4f compounds [Co(C5Me5)2][(C5Me5)2Ln(μ-S)2Mo(μ-S)2Ln(C5Me5)2], 1-Ln (Ln = Y, Gd, Tb, Dy), containing the highly polarizable MoS43- bridging unit. UV-Vis-NIR diffuse reflectance spectra and DFT calculations of 1-Ln reveal a low-energy metal-to-metal charge transfer transition assigned...

Human skin oils are significant scavengers of atmospheric oxidants in occupied indoor environments, and squalene is a major ozone-active constituent. Here, we present a combined spectroscopic and atomistic modeling approach to elucidate the conformational and orientational preferences of squalene at the air/oil interface and their implications for...

This book addresses the construction and application of the major types of basis sets for computational chemistry calculations. In addition to a general introduction, it includes mathematical basics and a discussion of errors arising from incomplete or inappropriate basis sets. The different chapters introduce local orbitals and orbital localizatio...

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 mul...

A thorough analysis of molecular vibrations in the binary system hydrogen chloride/water is presented considering a set of small mixed and pure clusters. In addition to the conventional normal mode analysis based on the diagonalization of the Hessian, anharmonic frequencies were obtained from the perturbative VPT2 and PT2-VSCF method using hybrid d...

We demonstrate for formic and acetic acid dissolved in water as examples that the binary quantum cluster equilibrium (bQCE) approach can predict acid strengths over the whole range of acid concentrations. The acid strength increases in a complex rather than a simple way with increasing mole fraction of the acid from 0 to 0.7, reflecting the complex...

We demonstrate that the binary quantum cluster equilibrium (bQCE) approach can predict acid strengths throughout the whole range of acid concentrations at the example of formic and acetic acid dissolved in water. We show that the acid strength increases in a complex instead of simple way with increasing mole fraction of the acids in the range of 0...

We applied the binary Quantum Cluster Equilibrium (bQCE) method to a number of alkylammonium-based protic ionic liquids in order to predict boiling points, vaporization enthalpies, and proton activities. The theory combines statistical thermodynamics of van-der-Waals-type clusters with ab initio quantum chemistry and yields the partition functions...

Ionic liquids raise interesting but complicated questions for theoretical investigations due to the fact that a number of different inter-molecular interactions, e.g., hydrogen bonding, long-range Coulomb interactions, and dispersion interactions, need to be described properly. Here, we present a detailed study on the ionic liquids ethylammonium ni...

We present an updated version of Peacemaker, a software package for performing neat and binary Quantum Cluster Equilibrium (QCE, bQCE) calculations. Peacemaker2 has been rewritten from scratch and is fast, robust, parallelized, and well-documented. Apart from sketching the implementation and introducing several improvements to bQCE theory, we calcu...

The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give...

We present a first-principles calculation and mechanistic characterization of the ion product of liquid water (KW), based on Quantum Cluster Equilibrium (QCE) theory with a variety of ab initio and density functional methods. The QCE method is based on T-dependent Boltzmann weighting of different-sized clusters and consequently enables the observat...

The well-established quantum cluster equilibrium (QCE) model provides a statistical thermodynamic framework to apply high-level ab initio calculations of finite cluster structures to macroscopic liquid phases using the partition function. So far, the harmonic approximation has been applied throughout the calculations. In this article, we apply an i...

The floating orbital molecular dynamics approach treats the basis functions' centers in ab initio molecular dynamics simulations variationally optimized in space rather than keeping them strictly fixed on nuclear positions. An implementation of the restricted theory for closed shell systems is already available (Perlt et al., Phys. Chem. Chem. Phys...

The Quantum Cluster Equilibrium model which has been developed within the past two decades is presented. It constitutes an alternative for the investigation of fluid phases and phase transitions. In that contribution, a conceptual overview is given. It is explained, how a limited number of molecular clusters is employed for the description of the l...

We introduce an alternative ab initio molecular dynamics simulation as a unification of Hartree-Fock molecular dynamics and the floating orbital approach. The general scheme of the floating orbital molecular dynamics method is presented. Moreover, a simple but sophisticated guess for the orbital centers is provided to reduce the number of electroni...

The preparation and characterization of three new mixed ligand macrocyclic [Ni2L2(L′)]+ complexes are described, where (L2)2– represents a supporting macrocyclic hexaaza-bis(phenylsulfonato) ligand and L′ a tetrazolato ligand. The complexes [Ni2(L2)(CN4H)]BPh4 (4), [Ni2(L2)(CN4Me)]BPh4 (5), and [Ni2(L2)(CN4Ph)]BPh4 (6) were synthesized by H2O2 oxid...

The established quantum cluster equilibrium approach is further developed in this work. The equations are reformulated to result in a one-parameter expression, i.e., with one of two empirical parameters eliminated. Instead of a parametrized constant mean field interaction we present two further approaches using temperature dependent mean field func...

The investigation of liquid phases by means of accurate electronic structure methods is a demanding task due to the high computational effort. We applied second-order Møller-Plesset perturbation theory and high-level quantum chemical calculations using the coupled-cluster method with single, double and perturbative triple excitations in combination...

An extension of the quantum cluster equilibrium theory to treat binary mixtures is introduced in this work. The necessary equations are derived and a possible implementation is presented. In addition an alternative sampling procedure using widely available experimental data for the quantum cluster equilibrium approach is suggested and tested. An il...

The quantum cluster equilibrium theory and its implementation into the freely available Peacemaker program are described in this paper. The important equations of the quantum cluster equilibrium with a constant mean field potential and an excluded volume are derived. The scheme of the consecutive iterations to obtain both natural variables (volume...

Treating the bulk phase with high-level ab initio methods, such as coupled cluster, is a nontrivial task because of the computational costs of these electronic structure methods. In this part of our hydrogen fluoride study we make use of the quantum cluster equilibrium method, which employs electronic structure input of small clusters and combines...

A multiscale approach with roots in electronic structure calculations relies on the good description of intermolecular forces. In this study we lay the foundations for a condensed phase treatment based on the electronic structure of hydrogen fluoride on a very high level of theory. This investigation comprises cluster calculations in a static quant...