Computer experiments on aqueous solutions. VII. Potential energy function for urea dimer and molecular dynamics calculation of 8 mol % aqueous solution of urea

Hideki Tanaka, Koichiro Nakanishi, Hidekazu Touhara

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Molecular dynamics calculation (MD) has been carried out for an aqueous solution of urea at 298.15 K and with experimental density value at ordinary pressure by the use of constant temperature technique developed previously. The total number of molecules is 216, of which 17 are urea. The mole fraction of urea in the solution is thus 0.078. For water-water and water-urea interactions, the MCY potential and previously determined potential have been used. A new urea-urea pair potential is determined by ab initio LCAO SCF calculations for more than 750 different dimer configurations with an STO-3G basis set and subsequent multiparameter optimization of the MO data to a 12-6-3-1 potential energy function. The MD calculation is extended up to 76 000 time steps and final 44 000 time steps (17.6 ps) are used to calculate both static and dynamic properties. Among other information, the following results are important and interesting: (1) Urea molecules exhibit appreciable self-association, (2) such association is possible with strong hydrogen bondings and this is in sharp contrast with the association of t-butanol through hydrophobic interaction studied previously, (3) there is no evidence that urea destroys structure of water, and (4) the decrease of self-diffusion coefficient of water in urea solution is appreciably smaller than that in the case of t-butanol solution.

Original languageEnglish
Pages (from-to)5184-5191
Number of pages8
JournalThe Journal of Chemical Physics
Volume82
Issue number11
Publication statusPublished - 1985
Externally publishedYes

Fingerprint

Potential energy functions
ureas
Dimers
Urea
Molecular dynamics
potential energy
dimers
molecular dynamics
aqueous solutions
Experiments
tert-Butyl Alcohol
Water
water
Association reactions
Molecules
dynamic characteristics
self consistent fields
molecules
Hydrogen bonds
diffusion coefficient

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Computer experiments on aqueous solutions. VII. Potential energy function for urea dimer and molecular dynamics calculation of 8 mol % aqueous solution of urea. / Tanaka, Hideki; Nakanishi, Koichiro; Touhara, Hidekazu.

In: The Journal of Chemical Physics, Vol. 82, No. 11, 1985, p. 5184-5191.

Research output: Contribution to journalArticle

@article{394ade73210f40d087c5053435728a27,
title = "Computer experiments on aqueous solutions. VII. Potential energy function for urea dimer and molecular dynamics calculation of 8 mol {\%} aqueous solution of urea",
abstract = "Molecular dynamics calculation (MD) has been carried out for an aqueous solution of urea at 298.15 K and with experimental density value at ordinary pressure by the use of constant temperature technique developed previously. The total number of molecules is 216, of which 17 are urea. The mole fraction of urea in the solution is thus 0.078. For water-water and water-urea interactions, the MCY potential and previously determined potential have been used. A new urea-urea pair potential is determined by ab initio LCAO SCF calculations for more than 750 different dimer configurations with an STO-3G basis set and subsequent multiparameter optimization of the MO data to a 12-6-3-1 potential energy function. The MD calculation is extended up to 76 000 time steps and final 44 000 time steps (17.6 ps) are used to calculate both static and dynamic properties. Among other information, the following results are important and interesting: (1) Urea molecules exhibit appreciable self-association, (2) such association is possible with strong hydrogen bondings and this is in sharp contrast with the association of t-butanol through hydrophobic interaction studied previously, (3) there is no evidence that urea destroys structure of water, and (4) the decrease of self-diffusion coefficient of water in urea solution is appreciably smaller than that in the case of t-butanol solution.",
author = "Hideki Tanaka and Koichiro Nakanishi and Hidekazu Touhara",
year = "1985",
language = "English",
volume = "82",
pages = "5184--5191",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "11",

}

TY - JOUR

T1 - Computer experiments on aqueous solutions. VII. Potential energy function for urea dimer and molecular dynamics calculation of 8 mol % aqueous solution of urea

AU - Tanaka, Hideki

AU - Nakanishi, Koichiro

AU - Touhara, Hidekazu

PY - 1985

Y1 - 1985

N2 - Molecular dynamics calculation (MD) has been carried out for an aqueous solution of urea at 298.15 K and with experimental density value at ordinary pressure by the use of constant temperature technique developed previously. The total number of molecules is 216, of which 17 are urea. The mole fraction of urea in the solution is thus 0.078. For water-water and water-urea interactions, the MCY potential and previously determined potential have been used. A new urea-urea pair potential is determined by ab initio LCAO SCF calculations for more than 750 different dimer configurations with an STO-3G basis set and subsequent multiparameter optimization of the MO data to a 12-6-3-1 potential energy function. The MD calculation is extended up to 76 000 time steps and final 44 000 time steps (17.6 ps) are used to calculate both static and dynamic properties. Among other information, the following results are important and interesting: (1) Urea molecules exhibit appreciable self-association, (2) such association is possible with strong hydrogen bondings and this is in sharp contrast with the association of t-butanol through hydrophobic interaction studied previously, (3) there is no evidence that urea destroys structure of water, and (4) the decrease of self-diffusion coefficient of water in urea solution is appreciably smaller than that in the case of t-butanol solution.

AB - Molecular dynamics calculation (MD) has been carried out for an aqueous solution of urea at 298.15 K and with experimental density value at ordinary pressure by the use of constant temperature technique developed previously. The total number of molecules is 216, of which 17 are urea. The mole fraction of urea in the solution is thus 0.078. For water-water and water-urea interactions, the MCY potential and previously determined potential have been used. A new urea-urea pair potential is determined by ab initio LCAO SCF calculations for more than 750 different dimer configurations with an STO-3G basis set and subsequent multiparameter optimization of the MO data to a 12-6-3-1 potential energy function. The MD calculation is extended up to 76 000 time steps and final 44 000 time steps (17.6 ps) are used to calculate both static and dynamic properties. Among other information, the following results are important and interesting: (1) Urea molecules exhibit appreciable self-association, (2) such association is possible with strong hydrogen bondings and this is in sharp contrast with the association of t-butanol through hydrophobic interaction studied previously, (3) there is no evidence that urea destroys structure of water, and (4) the decrease of self-diffusion coefficient of water in urea solution is appreciably smaller than that in the case of t-butanol solution.

UR - http://www.scopus.com/inward/record.url?scp=33846060787&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33846060787&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:33846060787

VL - 82

SP - 5184

EP - 5191

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 11

ER -