Ab initio approach to molecular crystals: A periodic Hartree–Fock study of crystalline urea

The electronic structure of crystalline urea (two molecules, 16 atoms per unit cell) is investigated at an ab initio level with CRYSTAL, a Hartree–Fock linear combination of atomic orbitals (LCAO) program for periodic systems. The influence of the basis set and of the computational parameters which control the treatment of the Coulomb and exchange series and the reciprocal space integration is documented; results include total and interaction energy, Mulliken analysis data and interaction (solid minus molecules) density maps, band structure, and density of states. The crystal field modifies the electronic structure of the isolated molecule, the main effect being an increase in the ionicity of bonds. The interaction energy obtained with a 6‐21** basis set is 28 kcal/mol, (16 kcal/mol after a correction of the basis set superposition error by using the counterpoise method) to be compared with 21±0.5 kcal/mol from experiment. This preliminary application shows that accurate ab initio calculations of hydrogen...

[1]  H. Graafsma,et al.  The influence of intermolecular interactions on the electron-density distribution. A comparison of experimental and theoretical results for a-oxalic acid dihydrate , 1988 .

[2]  A. Jansen,et al.  Dynamics of molecular crystals , 1986 .

[3]  Roberto Dovesi,et al.  Exact-exchange Hartree–Fock calculations for periodic systems. I. Illustration of the method† , 1980 .

[4]  Roberto Dovesi,et al.  The electronic structure of α-quartz: A periodic Hartree-Fock calculation , 1987 .

[5]  R. Dovesi,et al.  Exact-exchange Hartree-Fock calculations for periodic systems. III. Ground-state properties of diamond , 1980 .

[6]  R. Orlando,et al.  Treatment of the exchange interactions in Hartree-Fock LCAO calculations of periodic systems , 1988 .

[7]  P. C. Hariharan,et al.  The influence of polarization functions on molecular orbital hydrogenation energies , 1973 .

[8]  R. Dovesi,et al.  A periodic ab initio Hartree-Fock calculation on corundum , 1987 .

[9]  M. Spackman The electron distribution in silicon. A comparison between experiment and theory , 1986 .

[10]  R. K. McMullan,et al.  The crystal structure and molecular thermal motion of urea at 12, 60 and 123 K from neutron diffraction , 1984 .

[11]  P. P. Ewald Die Berechnung optischer und elektrostatischer Gitterpotentiale , 1921 .

[12]  S. F. Boys,et al.  The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors , 1970 .

[13]  B. C. Carlson,et al.  On the expansion of a Coulomb potential in spherical harmonics , 1950, Mathematical Proceedings of the Cambridge Philosophical Society.

[14]  D. Mullen Electron‐density distribution in urea. A multipolar expansion , 1980 .

[15]  Roberto Dovesi,et al.  Hartree-Fock study of lithium hydride with the use of a polarizable basis set , 1984 .

[16]  David Feller,et al.  Basis Set Selection for Molecular Calculations , 1986 .

[17]  H. Monkhorst,et al.  Complete Calculations of the Electronic Energies of Solids , 1969 .

[18]  R. Stewart,et al.  Theoretical and experimental studies of the charge density in urea , 1984 .

[19]  E. Stevens Comparison of theoretical and experimental electron density distributions of oxalic acid dihydrate , 1980 .

[20]  Clemens C. J. Roothaan,et al.  New Developments in Molecular Orbital Theory , 1951 .

[21]  SuzukiKeisuke,et al.  Vapor Pressures of Molecular Crystals. XI. Vapor Pressures of Crystalline Urea and Diformylhydrazine. Energies of Hydrogen Bonds in these Crystals , 1956 .

[22]  C. Scheringer The electron‐density distribution in silicon , 1980 .

[23]  D. Feil,et al.  Electron density distributions in hydrogen bonds: A local density‐functional study of α‐oxalic acid dihydrate and comparison with experiment , 1988 .

[24]  J. Pople,et al.  Self‐Consistent Molecular‐Orbital Methods. I. Use of Gaussian Expansions of Slater‐Type Atomic Orbitals , 1969 .

[25]  R. Dovesi On the role of symmetry in the ab initio hartree‐fock linear‐combination‐of‐atomic‐orbitals treatment of periodic systems , 1986 .

[26]  R. Dovesi,et al.  Treatment of Coulomb interactions in Hartree-Fock calculations of periodic systems , 1983 .

[27]  P. Wormer,et al.  Ab initio studies of the interactions in Van der Waals molecules , 1980 .