Stabilization of hydrate structure H by N2 and CH4 molecules in 435663 and 512 cavities, and fused structure formation with 51268 cage: A theoretical study

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Abstract

At the MP2/6-31G*//HF/6-31G* level calculation, a dodecahedral water cluster (512, 20-mer) in hydrate structure H (sH) is more stable than an irregular dodecahedral cluster (435663, 20-mer) by about 3.0 kcal/mol. However, in the presence of CH4 and N2 molecules in cavity, the irregular dodecahedron becomes significantly more stable than a dodecahedral cluster. Even though a large 51268 water cluster (36-mer) in sH is less stable (stabilization energy per H2O) than a tetrakaidecahedral (51262, 24-mer, hydrate I) or a hexakaidecahedral (51264, 28-mer, hydrate II) cluster, significant stabilization in sH is achieved by fused structure formation involving 51268 clusters. While maximum stabilization is achieved by a pentagonal ring sharing between 51268 and 512 cages, no stabilization is achieved by a pentagonal ring sharing between two 435663 cages. Possible mechanism of hydrate formation has also been discussed.

Original languageEnglish (US)
Pages (from-to)7429-7434
Number of pages6
JournalJournal of Physical Chemistry A
Volume105
Issue number31
StatePublished - Aug 9 2001

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Hydrates
hydrates
Stabilization
stabilization
cavities
Molecules
molecules
Water
rings
water

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

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title = "Stabilization of hydrate structure H by N2 and CH4 molecules in 435663 and 512 cavities, and fused structure formation with 51268 cage: A theoretical study",
abstract = "At the MP2/6-31G*//HF/6-31G* level calculation, a dodecahedral water cluster (512, 20-mer) in hydrate structure H (sH) is more stable than an irregular dodecahedral cluster (435663, 20-mer) by about 3.0 kcal/mol. However, in the presence of CH4 and N2 molecules in cavity, the irregular dodecahedron becomes significantly more stable than a dodecahedral cluster. Even though a large 51268 water cluster (36-mer) in sH is less stable (stabilization energy per H2O) than a tetrakaidecahedral (51262, 24-mer, hydrate I) or a hexakaidecahedral (51264, 28-mer, hydrate II) cluster, significant stabilization in sH is achieved by fused structure formation involving 51268 clusters. While maximum stabilization is achieved by a pentagonal ring sharing between 51268 and 512 cages, no stabilization is achieved by a pentagonal ring sharing between two 435663 cages. Possible mechanism of hydrate formation has also been discussed.",
author = "Arshad Khan",
year = "2001",
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language = "English (US)",
volume = "105",
pages = "7429--7434",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
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T1 - Stabilization of hydrate structure H by N2 and CH4 molecules in 435663 and 512 cavities, and fused structure formation with 51268 cage

T2 - A theoretical study

AU - Khan, Arshad

PY - 2001/8/9

Y1 - 2001/8/9

N2 - At the MP2/6-31G*//HF/6-31G* level calculation, a dodecahedral water cluster (512, 20-mer) in hydrate structure H (sH) is more stable than an irregular dodecahedral cluster (435663, 20-mer) by about 3.0 kcal/mol. However, in the presence of CH4 and N2 molecules in cavity, the irregular dodecahedron becomes significantly more stable than a dodecahedral cluster. Even though a large 51268 water cluster (36-mer) in sH is less stable (stabilization energy per H2O) than a tetrakaidecahedral (51262, 24-mer, hydrate I) or a hexakaidecahedral (51264, 28-mer, hydrate II) cluster, significant stabilization in sH is achieved by fused structure formation involving 51268 clusters. While maximum stabilization is achieved by a pentagonal ring sharing between 51268 and 512 cages, no stabilization is achieved by a pentagonal ring sharing between two 435663 cages. Possible mechanism of hydrate formation has also been discussed.

AB - At the MP2/6-31G*//HF/6-31G* level calculation, a dodecahedral water cluster (512, 20-mer) in hydrate structure H (sH) is more stable than an irregular dodecahedral cluster (435663, 20-mer) by about 3.0 kcal/mol. However, in the presence of CH4 and N2 molecules in cavity, the irregular dodecahedron becomes significantly more stable than a dodecahedral cluster. Even though a large 51268 water cluster (36-mer) in sH is less stable (stabilization energy per H2O) than a tetrakaidecahedral (51262, 24-mer, hydrate I) or a hexakaidecahedral (51264, 28-mer, hydrate II) cluster, significant stabilization in sH is achieved by fused structure formation involving 51268 clusters. While maximum stabilization is achieved by a pentagonal ring sharing between 51268 and 512 cages, no stabilization is achieved by a pentagonal ring sharing between two 435663 cages. Possible mechanism of hydrate formation has also been discussed.

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