DL_MONTE: a general purpose program for parallel Monte Carlo simulation

Figures & data

Figure 1 The time taken for two representative simulations. The first is for GCMC simulation of CO₂ in zeolite-A (approximately 2400 zeolite ions and 100 CO₂ molecules) and the second for the NPT simulation of bulk MgO (512 ions). Both calculations used the Ewald summation technique. The zeolite simulations were carried out on the UK supercomputing facility, HECToR, a Cray XE6 and the MgO simulation on the IBM Idataplex, Blue Wonder, at Daresbury Laboratory. All times are referenced to those taken on a single core.

Figure 2 The enthalpy of forming, ΔH (kJ mol^–1), for different size nanoparticles. All calculations were carried out at 800 K.

Figure 3 (Colour online) Structure of 21,952 ion nanoparticle containing 5% Mn²⁺ ions. The Mn²⁺ ions preferentially decorate corners, edges and faces. Mg²⁺, Mg²⁺ and O^2– are coloured green, purple and red, respectively.

Figure 4 The calculated phase diagram of the 1728 nanoparticle. The solid line is the binodal and the dashed line the spinodal.

Figure 5 The consolute temperature T_c as a function of nanoparticle size (total number of ions).

Figure 6 The average number of adsorbed water molecules, as a function of the chemical potential, . The calculation of is described in the text. All the calculations were performed at 350 K.

Figure 7 (Colour online) The distribution of water molecule energies determined at  kJ mol^–1 and  kJ mol^− 1. The energies displayed are taken from representative simulations at 275 K.

Figure 8 (Colour online) The structure of water molecules at the surface for (a)  = 69 and (b)  = 86. The Mg²⁺ and O^2– ions in the substrate are coloured green and red, respectively. The O and H atoms in the water molecule are coloured blue and white, respectively.

Figure 9 (Colour online) Structure of (a) FAU viewed along (1 1 0) and (b) MFI viewed along (0 1 0) and (1 0 0). Grey colour represents silicon and red colour represents oxygen.

Table 1 Simulated zeolite lattice parameters compared to experiment.

	Calculated lattice parameters (Å)			Experimental lattice parameters (Å)
	a	b	c	a	b	c
Siliceous MFI^a	20.047	19.935	13.378	20.051	19.876	13.368
Siliceous FAU^b	24.056	24.056	24.056	24.258	24.258	24.258
Na-FAU^c	24.416	24.412	24.421	24.638	24.638	24.638
K-FAU^d	24.543	24.455	24.424	24.998	24.998	24.998

^a Experimental data from Artioli et al. [50].

^b Experimental data from Hriljac et al. [51].

^c Experimental data from Wise [52].

^d Experimental data from Lim et al. [53].

Figure 10 (Colour online) Adsorption of CO₂ in Na-FAU (a) adsorption isotherms, (b) adsorption isosteres and (c) heats of adsorption.

Figure 11 (Colour online) Adsorption isotherms of CO₂ in siliceous MFI, coloured according to temperature. Data points are our simulations, line is experimental data from Yamazaki et al. [54] at 273 K.

Table 2 Sensitivity on potential parameters of the number of CO₂ molecules adsorbed at two test pressures, 5 and 25 bar, to compare with experimental data from Maurin et al. [41].

Potential modifications					N, molec. CO2/u.c.
Test	rAl (Å)	ϵ Oz	(Å)	rNa (Å)	P = 5 bar (target = 93)	P = 25 bar (target = 107)
Base	3.706	0.006739	3.5532	2.6378
1		+5%				91.7
2		+11%			88.6	94.9
3		+20%				93.8
4		+25%			92.9	93.7
5	+4%	+5%				93.5
6	+4%	+11%			90.6	93.3
7	+4%	+20%				92.4
8	+4%	+25%			90.5	92.0
9	+4%	+11%	− 1.4%		90.9	103.3
10	+4%	+11%	− 2.8%		91.7	100.7
11	+4%	+11%	− 4.2%		93.8	101.9
12	+4%	+25%	− 4.2%		94.0	102.4
13	+4%	+11%		− 10%	95.8	103.2
14	+4%	+11%		− 15%	96.9	103.6
15	+4%	+11%		− 20%	99.4	105.2

Figure 12 (Colour online) Heat of adsorption of CO₂ in Na-FAU, Si:Al ratio = 1. Green: test 13, blue: test 14, red: test 15, orange: experimental data from Maurin et al. [41].

Table 3 Lennard-Jones potential parameters and partial charges.

	ϵ (eV)	r(Å)	Charge
Zeolites
Si	7.98817 × 10^− 8	3.7061	2.1
Al	7.98817 × 10^− 8	3.8564	1.575
Ozs	0.006739	3.5532	− 1.05
Oza	0.007501	3.5532	− 1.16875
Na	0.005641	2.2421	1.0
K	0.004336	3.1810	1.0
CO2–CO2
Oc	0.006930	3.4044	− 0.3256
C	0.002421	3.0946	0.6512
CO2-zeolite
Oc	0.006739	3.5532	− 0.3256
C	0.002421	3.3191	0.6512
Three-body terms	(eVÅ^2)	θijk (°)
O–Si–O	12.1	109.47
O–Al–O	12.1	109.47

Note: Z, zeolite; C, CO₂; s,siliceous zeolite; a, aluminosilicate zeolite.

Figure 13 (Colour online) Adsorption isotherm of CO₂ in Na-FAU with Si:Al ratio = 1 (green) and Si:Al ratio = 1.18 (red and blue) at 303.2 K. Data points are our simulations, blue line is represents experimental data from Pillai et al. [55].

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