About

Ludwik Adamowicz is a professor at the University of Arizona, affiliated with the Department of Chemistry and Biochemistry. He holds a Master of Science degree from Warsaw University (1973) and a Ph.D. from the Institute of Physical Chemistry of the Polish Academy of Sciences (1977). His research has been focused on the development and application of quantum chemical theoretical methods for more accurate determination of the stationary and dynamic quantum states of molecular systems. His work encompasses theory formulation, computational implementation, and application calculations, with recent progress in computational capabilities enabling the employment of new theoretical techniques to larger polyatomic molecules. This progress leads to more reliable predictions of molecular properties and structures, contributing significantly to the fields of biophysics, chemical physics, materials, polymer chemistry, nucleic acids, and genomes, as well as spectroscopy, molecular structure, theory, modeling, and simulation.

Research topics

• Computer Science
• Physics
• Physical chemistry
• Computational chemistry
• Atomic physics
• Chemistry
• Quantum mechanics
• Thermodynamics
• Materials science

Selected publications

• Nanocomposites of MoS2 and anticancer thioderivatives of purine nucleobases: Insight into molecular interactions noticeable for drug delivery applications

  Low Temperature Physics · 2026-04-23

  article

  Two-dimensional nanomaterials, specifically MoS2 nanosheets, are at the forefront of the current biomedical-related nanoscience research due to their great potential in biosensing, drug delivery, and biocatalysis. Their unique physicochemical properties and biocompatibility make MoS2 a prospective platform for anticancer drug delivery and photothermal therapy of cancers. Among physical methods actively used for the nanomaterial characterization, the modern mass spectrometry techniques, in particular the laser desorption/ionization (LDI) method, demonstrate high efficiency and informativeness. In this study, we examine intermolecular interactions between the components of nanocomposites of the MoS2 nanoparticles with anticancer thioderivatives of purine nucleobases, 6-thiopurine (TP) and 2-thioadenine (TA), using LDI mass spectrometry and theoretical quantum-chemical modeling. These interactions are important to the properties associated with drug delivery. The results of the LDI mass spectrometric examination of the nanocomposites show that a certain amount of the drug molecules retain their molecular integrity within the nanocomposite, which is a prerequisite for the therapeutic efficacy of the anticancer nanosystems studied in this work. At the same time, a detailed analysis of the LDI mass spectra obtained in the study allows us to determine that some molecules of TP and TA undergo chemical transformations, including oxidation, in the presence of catalytically active MoS2 particles. Ab initio DFT modeling (M06-2X) is employed to determine the structural configurations and binding energies of the nanocomplexes of MoS2 with the studied drug molecules. The results of the calculations show that TA and TP molecules can form stable stacking complexes with the surface of the MoS2 nanosheets, as well as covalent complexes with the edges of the sheets. The present study shows that the chemical alteration of the anticancer thioderivatives induced by MoS2 may modulate the therapeutic activity of thiol-based drugs. This effect can be important for future biomedical applications of nanocomposites of MoS2 with TP and TA.

  PublisherDOI

• Tegafur and lamivudine complexes with MoS2: Structures, interaction energies, and vibrational spectra

  Low Temperature Physics · 2026-04-23

  articleSenior author

  We study the structures, interaction energies, and vibrational spectra of the complexes of two drug molecules (lamivudine and tegafur) with pristine MoS2, as well as with MoS2 containing surface point defects. The potential of MoS2 as a platform for drug delivery, such as tegafur and lamivudine, is assessed. An exhaustive search for tegafur and lamivudine conformers is performed using the MP2/aug-cc-pVDZ method and four tegafur and sixteen lamivudine conformers are found. Calculations of MoS2 complexes with lower energy conformers of the studied molecules are performed using the DFT/M06-2X method. We demonstrate the possibility of formation of a wide variety of complexes. Complexes with a pristine surface are stabilized only by stacking interactions and have relatively low absolute values of the interaction energies. Accounting for the aqueous environment significantly weakens the stacking interaction to approximately –2 kcal/mol. For complexes stabilized by coordination bonds, the interaction energies are in the range from –90 to –40 kcal/mol. It is sufficient for binding tegafur and lamivudine molecules to MoS2, even taking into account the weakening of the interaction in water to approximately –20 kcal/mol. Analysis of the vibrational spectra of the tegafur and lamivudine complexes with MoS2 allows us to identify spectral markers indicating the formation of the complexes.

  PublisherDOI

• Triplet-state transitions in beryllium: Accurate energies and oscillator strengths

  Physical review. A/Physical review, A · 2025-11-03

  article

  We present highly accurate variational calculations of triplet excited states of the beryllium atom using all-electron explicitly correlated Gaussian basis sets. The employed approach that treats the electrons and the nucleus on the same footing enables precise determination of the energy spectrum, wave functions, and transition properties of low-lying ${}^{3}{S}^{e}$ and ${}^{3}{P}^{o}$ states of the naturally occurring $^{9}\mathrm{Be}$ isotope and the model ${}^{\ensuremath{\infty}}\mathrm{Be}$ system. Benchmark-quality total and transition energies, as well as oscillator strengths determined in both the length and velocity gauges, are reported. The results are compared with available theoretical and experimental data. The comparison shows excellent agreement of the present results with the experiment. They also provide refinement for the values where discrepancies had existed before.

  PublisherDOI

• Rothe Time Propagation for Coupled Electronic and Rovibrational Quantum Dynamics

  ArXiv.org · 2025-03-12

  preprintOpen access

  When time-propagating a wave packet representing a molecular system interacting with strong attosecond laser pulses, one needs to use an approach that is capable of describing intricate coupled electronic-nuclear events that require departure from the conventional adiabatic Born-Oppenheimer (BO) approximation. Hence, the propagation should be carried out simultaneously for the electrons and nuclei, treating both particle types on an equal footing \emph{without} invoking the BO approximation. In such calculations, in order to achieve high accuracy, the wave packet needs to be expanded in basis functions that explicitly depend on interparticle distances, such as all-particle explicitly correlated Gaussians (ECGs). In our previous work, we employed basis sets consisting of ECGs with optimizable complex exponential parameters to fit time-dependent wave functions obtained from grid-based propagations of two model systems: a nucleus in a Morse potential and an electron in a central-field Coulomb-like potential, subjected to intense laser pulses. In this work, we present a proof-of-principle study of the time propagation of linear combinations of ECGs for these two models using Rothe's method. It is shown that the approach very closely reproduce the virtually exact results of grid-based propagation for both systems. This provides further evidence that ECGs constitute a viable alternative to purely grid-based simulations of coupled nuclear-electronic dynamics driven by intense laser pulses.

  PublisherOA PDFDOI

• Particle dynamics in stream channels from molecular dynamics

  Physics of Fluids · 2025-04-01

  articleSenior author

  Hydrodynamics is an important scientific field for investigating and characterizing fluids. This work presents a novel method for studying fluids at the atomic level using molecular dynamics. The fluids flow in closed channels and under conditions of pressure and temperature. The method has the advantage of avoiding the difficulties traditionally encountered in formulating and solving the Navier-Stokes equations in combination with periodic boundary conditions. In this work, the stream channels are simulated with confining potentials, making the method efficient, general, and flexible enough to represent different channel topologies. It is illustrated with the simulation of water molecules flowing inside an elongated toroidal pipeline, with many small gold clusters suspended in the fluid. The clusters coalesce and form aggregates with average sizes that depend on the water velocity. The results suggest a new experimental approach for the formation of large clusters from small ones by tuning the flux rate in the laboratory experiments. The method is the first of its kind and opens new horizons for studying hydrodynamic processes at the atomic level employing first-principles theory.

  PublisherDOI

• Noncovalent complexes of dimethyl sulfoxide with anticancer thioderivatives of purine nucleobases: insights into drug delivery mechanisms

  Journal of Molecular Structure · 2025-05-01

  articleSenior author
  PublisherDOI

• Non-Born–Oppenheimer Electronic Structure and Relativistic Effects in the Ground States of BH and BH⁺

  The Journal of Physical Chemistry A · 2025-02-03 · 1 citations

  articleSenior authorCorresponding

  In this work, we report benchmark variational calculations for the boron monohydride (BH) molecule and its cation (BH+). The solutions to the nonrelativistic Schrödinger equations for these systems are obtained using a variational method without assuming the Born–Oppenheimer (BO) approximation, which separates electronic and nuclear motions. The ground-state wave functions for both the eight-particle (two nuclei and six electrons) BH molecule and the seven-particle (two nuclei and five electrons) BH+ ion are expanded in terms of all-particle explicitly correlated Gaussian with prefactors that effectively capture nucleus–nucleus correlation effects. These nonrelativistic non-BO wave functions are used to compute leading-order relativistic corrections to the total energies via perturbation theory, as well as to estimate leading-order quantum electrodynamics (QED) effects. The resulting total, dissociation, and ionization energies of BH represent the most accurate rigorously obtained theoretical values to date.

  PublisherDOI

• Rothe Time Propagation for Coupled Electronic and Rovibrational Quantum Dynamics

  The Journal of Physical Chemistry A · 2025-06-09 · 1 citations

  articleOpen access

  When time-propagating a wave packet representing a molecular system interacting with strong attosecond laser pulses, one needs to use an approach that is capable of describing intricate coupled electronic-nuclear events that require departure from the conventional adiabatic Born–Oppenheimer (BO) approximation. Hence, the propagation should be carried out simultaneously for the electrons and nuclei, treating both particle types on an equal footing without invoking the BO approximation. In such calculations, in order to achieve high accuracy, the wave packet needs to be expanded in basis functions that explicitly depend on interparticle distances, such as all-particle explicitly correlated Gaussians (ECGs). In our previous work, we employed basis sets consisting of ECGs with optimizable complex exponential parameters to fit time-dependent wave functions obtained from grid-based propagations of two model systems: a nucleus in a Morse potential and an electron in a central-field Coulomb-like potential, subjected to intense laser pulses. In this work, we present a proof-of-principle study of the time propagation of linear combinations of ECGs for these two models using Rothe’s method. It is shown that the approach very closely reproduces the virtually exact results of grid-based propagation for both systems. This provides further evidence that ECGs constitute a viable alternative to purely grid-based simulations of coupled nuclear-electronic dynamics driven by intense laser pulses.

  PublisherDOI

• Binding of native DNA to MoS2 nanoflakes: The role of defects and edge atoms of MoS2 nanostructures in their biofunctionalization

  Low Temperature Physics · 2025-10-01 · 1 citations

  article

  In this work, the binding of native DNA to MoS2 nanoflakes (FLs) was studied by using UV–visible absorption spectroscopy, thermal denaturation method, transmission electron microscopy (TEM), temperature-dependent dynamic light scattering (DLS), and the DFT computational-chemistry method. Analysis of the experimental data: TEM images and thermal denaturation measurements showed the binding of the biopolymer with MoS2 FLs. An increase in the melting temperature of DNA and a decrease in the hyperchromic coefficient at binding with MoS2 FLs indicate the formation of the DNA:MoS2 FL nanoassemblies due, primarily, to the covalent interaction of the oxygen atoms of the phosphate groups of DNA with the MoS2 FLs. Possible complexes of a nucleotide fragment (ribose-phosphate group) with MoS2 nanolayer are considered and calculated employing the DFT method. Different structures of these complexes are optimized, and the interaction energies between components are determined. Special attention in calculations is focused on the binding of this nucleotide fragment with Mo atoms located at the edge of the MoS2 nanolayer and with point structural defects of the MoS2 surface containing the S vacancy. Based on this calculation and experimental observation, a mechanism of binding of native DNA to MoS2 FLs has been proposed, in which their conjugation begins with point contacts of DNA phosphate groups with Mo atoms (at the edge or/and in defects) through the formation of a strong coordination bond. The results indicate the critical role of defects and edge atoms of MoS2 FLs in their biofunctionalization.

  PublisherDOI

• Gaussians for Electronic and Rovibrational Quantum Dynamics

  arXiv (Cornell University) · 2024-01-22

  preprintOpen access

  The assumptions underpinning the adiabatic Born-Oppenheimer (BO) approximation are broken for molecules interacting with attosecond laser pulses, which generate complicated coupled electronic-nuclear wavepackets that generally will have components of electronic and dissociation continua as well as bound-state contributions. The conceptually most straightforward way to overcome this challenge is to treat the electronic and nuclear degrees of freedom on equal quantum-mechanical footing by not invoking the BO approximation at all. Explicitly correlated Gaussian (ECG) basis functions have proved successful for non-BO calculations of stationary molecular states and energies, reproducing rovibrational absorption spectra with very high accuracy. In this paper, we present a proof-of-principle study of the ability of fully flexible ECGs (FFECGs) to capture the intricate electronic and rovibrational dynamics generated by short, high-intensity laser pulses. By fitting linear combinations of FFECGs to accurate wave function histories obtained on a large real-space grid for a regularized 2D model of the hydrogen atom and for the 2D Morse potential we demonstrate that FFECGs provide a very compact description of laser-driven electronic and rovibrational dynamics.

  PublisherOA PDFDOI

Recent grants

• A multireference coupled-cluster method for ground and excited states calculations of interstellar molecules

  NSF · $435k · 2019–2025

• U.S.-Poland Cooperative Research: Relativistic Molecular Quantum Mechanics Calculations without the Non-Born-Oppenheimer Approximation

  NSF · $39k · 2003–2007

• Rigorous Non-Born-Oppenheimer Variational Calculations of H3+ and Its Isotopomers

  NSF · $370k · 2005–2009

• Catalyzing new international collaboration. US-Taiwan collaboration of experimental and theoretical study of rovibrational spectra of small hydrogen-containing molecules and ions.

  NSF · $46k · 2015–2017

Frequent coauthors

• S. G. Stepanian

  B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine

  276 shared

• Monika Stanke

  Nicolaus Copernicus University

  145 shared

• Sergiy Bubin

  Nazarbayev University

  124 shared

• Zdeněk Slanina

  111 shared

• Guido Maes

  KU Leuven

  93 shared

• Johan Smets

  Procter & Gamble (Belgium)

  91 shared

• V. А. Karachevtsev

  84 shared

• Filip Uhlı́k

  Charles University

  75 shared