Semiempirical quantum-chemical calculations on the lattice energies of organic molecular crystals

2002 ◽  
Vol 58 (s1) ◽  
pp. c195-c195
Author(s):  
G. Raabe
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Molecular Crystals ◽  
Organic Molecular Crystals ◽  
Lattice Energies ◽  
Semiempirical Quantum Chemical Calculations

scholarly journals The Use of Quantum Chemical Semiempirical Methods to Calculate the Lattice Energies of Organic Molecular Crystals. Part I: The Three Polymorphs of Glycine

2000 ◽  
Vol 55 (6-7) ◽  
pp. 609-615 ◽  
Author(s):  
Gerhard Raabe
Keyword(s):  
Quantum Chemical ◽  
Chemical Method ◽  
Molecular Crystals ◽  
Lattice Energy ◽  
Potential Method ◽  
Electrostatic Energy ◽  
Semiempirical Methods ◽  
Quantum Chemical Method ◽  
Organic Molecular Crystals ◽  
Lattice Energies

Abstract A method to calculate the lattice energies of organic molecular crystals is described. It is based on the semiempirical quantum chemical MINDO/3 approximation but might also be used within the framework of any other quantum chemical method. The lattice energy is approximated by the sum of dispersion-, induction-, exchange repulsion-, and electrostatic energy. Different, however, from other schemes employed in this field, like for example the atom-atom-potential method, the variables in the expression for the lattice energy have not been fitted to reproduce experimental values and, therefore, the single contributions retain their original physical meaning. Moreover, the method offers the advantage that it may be directly applied to all compounds that can be treated within the framework of the underlying quantum chemical method. Thus, time consuming readjustment of the entire parameter set upon extension of the group of target molecules by another class of compounds becomes obsolete. As an example, the lattice energies of the three polymorphs of glycine are calculated.

NANOPACK: Parallel codes for semiempirical quantum chemical calculations of large systems in thesp- andspd-basis

2002 ◽  
Vol 88 (4) ◽  
pp. 449-462 ◽  
Author(s):  
Parvaz K. Berzigiyarov ◽  
Valentin A. Zayets ◽  
Ilya Ya. Ginzburg ◽  
Vladimir F. Razumov ◽  
Elena F. Sheka
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Large Systems ◽  
Semiempirical Quantum Chemical Calculations

The Electronic and Non-linear Optical Properties of Oxo-titanium Phthalocyanines

1999 ◽  
Vol 03 (05) ◽  
pp. 331-338 ◽  
Author(s):  
FRYAD HENARI ◽  
ANDREW DAVEY ◽  
WERNER BLAU ◽  
P. HAISCH ◽  
M. HANACK
Keyword(s):  
Optical Properties ◽  
Electronic Properties ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Non Linear ◽  
Linear Behaviour ◽  
Linear Optical Properties ◽  
Linear Optical ◽  
Semiempirical Quantum Chemical Calculations

The valence electronic properties of some unsubstituted and peripherally substituted oxo-titanium phthalocyanines are reported. Semiempirical quantum chemical calculations show that the nature of peripheral substituents has a strong bearing on the valence electronic properties, including the state dipole moments and absorption wavelength. The non-linear optical response was measured around the the Q-band resonance. The effect of different substituents and substitution patterns on the non-linear behaviour of the samples was determined. The combined results suggest that tuning of electronic and optical properties is effectively achieved by functionalization of the edges of the conjugated ring.

scholarly journals An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics

2016 ◽  
Vol 72 (4) ◽  
pp. 477-487 ◽  
Author(s):  
Edward O. Pyzer-Knapp ◽  
Hugh P. G. Thompson ◽  
Graeme M. Day
Keyword(s):  
Force Field ◽  
Crystal Structures ◽  
Force Fields ◽  
Molecular Crystals ◽  
Intermolecular Force ◽  
Organic Molecular Crystals ◽  
Organic Solid ◽  
Lattice Energies ◽  
Validation Set ◽  
Unit Cell Dimensions

We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%.

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