Molecular dynamics study of tridymite

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Marco E. Ciriotti
Messaggi: 24492
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Molecular dynamics study of tridymite

Messaggio da Marco E. Ciriotti » mar 01 mag, 2018 13:55

Referenza:
▪ Takada, A., Glaser, K.J., Bell, R.G., Catlow, C.R.A, (2018): Molecular dynamics study of tridymite. IUCrJ, 5, 325-334.

Abstract:
Polymorphic structural changes in tridymite have been investigated by molecular dynamics simulation. The main polymorphic transitions were reproduced and their mechanisms are explained.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Luciano Vaccari
Messaggi: 10433
Iscritto il: mer 30 giu, 2004 8:23
Località: Via Pietro Giusti 23 41043 Formigine -MO-

Re: Molecular dynamics study of tridymite

Messaggio da Luciano Vaccari » mer 02 mag, 2018 9:18

Ci sarà un pdf che tu sappia?
Ben oltre le idee di giusto e di sbagliato c'è un campo. Ti aspetterò laggiù.
(Jalaluddin Rumi- XIII sec.)

Luciano
Socio AMI zona Modena
(Formigine)

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Marco E. Ciriotti
Messaggi: 24492
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Molecular dynamics study of tridymite

Messaggio da Marco E. Ciriotti » mer 02 mag, 2018 10:02

Sì, sì. I testi dell'IUCrJ sono open access.
Lo puoi scaricare da qui: http://journals.iucr.org/m/issues/2018/03/00/zx5010/

Qui l'abstract completo:

Referenza:
▪ Takada, A., Glaser, K.J., Bell, R.G., Catlow, C.R.A, (2018): Molecular dynamics study of tridymite. IUCrJ, 5, 325-334.

Abstract:
Structural changes in tridymite have been investigated by molecular dynamics simulation. Two thermal processes were carried out, one cooling from the high-temperature hexagonal structure of tridymite (HP-tridymite) and the other heating from the low-temperature monoclinic structure of tridymite (MX1-tridymite). The former process showed that HP, LHP (low-temperature hexagonal structure), OC (orthorhombic structure with C2221 symmetry) and OP (orthorhombic structure with P212121 symmetry)-like structures appeared in sequence. In contrast, the latter process showed that MX1, OP, OC, LHP and HP-like structures appeared in sequence. Detailed analysis of the calculated structures showed that the configuration underwent stepwise changes associated with several characteristic modes. First, the structure of HP-tridymite determined from diffraction experiments was identified as a time-averaged structure in a similar manner to β-cristobalite, thus indicating the important role of floppy modes of oxygen atoms at high temperature – one of the common features observed in silica crystals and glass. Secondly, the main structural changes were ascribed to a combination of distortion of the six-membered rings in the layers and misalignment between layers. We suggest that the slowing down of floppy oxygen movement invokes the multistage emergence of structures with lower symmetry on cooling. This study therefore not only reproduces the sequence of the main polymorphic transitions in tridymite, except for the appearance of the monoclinic phase, but also explains the microscopic dynamic structural changes in detail.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Luciano Vaccari
Messaggi: 10433
Iscritto il: mer 30 giu, 2004 8:23
Località: Via Pietro Giusti 23 41043 Formigine -MO-

Re: Molecular dynamics study of tridymite

Messaggio da Luciano Vaccari » gio 03 mag, 2018 8:35

Grazie molte Marco.
Ben oltre le idee di giusto e di sbagliato c'è un campo. Ti aspetterò laggiù.
(Jalaluddin Rumi- XIII sec.)

Luciano
Socio AMI zona Modena
(Formigine)

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