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Developing ab initio quality force fields from condensed phase quantum-mechanics/molecular-mechanics calculations through the adaptive force matching method
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10.1063/1.2965882
/content/aip/journal/jcp/129/6/10.1063/1.2965882
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/6/10.1063/1.2965882

Figures

Image of FIG. 1.
FIG. 1.

Scatter plot of forces at the B3LYP level of theory using the 6-311G (blue circles), aug-cc-pvdz (black crosses), aug(dz)-cc-pvtz (green triangles), and aug-cc-pvtz (red squares) basis sets. The axis is the B3LYP/aug-cc-pvqz result. Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the black diagonal lines if the different basis sets resulted in identical atomic forces.

Image of FIG. 2.
FIG. 2.

Scatter plot of forces at the MP2 level of theory using the 6-311G (blue circles), aug-cc-pvdz (black crosses), and aug(dz)-cc-pvtz (green triangles) basis sets. The axis is the MP2/aug-cc-pvtz result. Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the black diagonal lines if the different basis sets resulted in identical atomic forces.

Image of FIG. 3.
FIG. 3.

Scatter plot of forces at the BLYP/aug-cc-pvdz (red circles), PBE (green crosses), and the B3LYP/aug-cc-pvdz (blue pluses) levels of theory. The axis is the MP2/aug-cc-pvdz result. Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the black diagonal lines if the different methods resulted in identical atomic forces.

Image of FIG. 4.
FIG. 4.

Scatter plot of forces at the MP2/aug-cc-pvdz level of theory. The axis is the QCISD/aug-cc-pvdz result. Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the diagonal lines if the MP2 and QCISD forces are identical.

Image of FIG. 5.
FIG. 5.

Scatter plots of forces on the central molecules with (blue circles), (red triangles), and (black crosses). The axis corresponds to the forces for . Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the black diagonal lines if the atomic forces on the central molecule were the same for each of the cluster sizes considered.

Image of FIG. 6.
FIG. 6.

Scatter plot of the forces for the (red circles) and SPCFw (blue crosses). The axis corresponds to the ab initio MP2 forces. Panel (a) shows the atomic forces, panel (b) shows net molecular forces, and panel (c) shows net molecular torques multiplied by . All the points would lie on the green diagonal lines if the different models predict forces identical to the MP2 ab initio forces.

Image of FIG. 7.
FIG. 7.

Site-site RDFs at the zeroth, first, and second generations obtained from AFM using MP2/aug-cc-pvdz forces. The RDFs from our final force field is also shown together with experimental results. The blue thick solid lines with error bars are experimental results from Ref. 34.

Image of FIG. 8.
FIG. 8.

Comparison of the RDFs from with those from CPMD simulation of Lee and Tuckerman (Ref. 37). The experimental RDFs are also plotted.

Image of FIG. 9.
FIG. 9.

Site-site RDFs from the final force fields from the MP2, BLYP, and B3LYP methods shown together with experimental RDFs.

Image of FIG. 10.
FIG. 10.

Infrared spectra from simulations with the , , and force fields shown together with the experimental results.

Tables

Generic image for table
Table I.

Parameters for the force fields and for the , , and force fields. The quantities and refer to the equilibrium OH and HOH intramolecular bond length and angle, respectively. We also show the parameters for the SPCFw model (Ref. 33) for comparison.

Generic image for table
Table II.

Thermodynamic properties calculated from our final models.

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/content/aip/journal/jcp/129/6/10.1063/1.2965882
2008-08-12
2014-04-25
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Developing ab initio quality force fields from condensed phase quantum-mechanics/molecular-mechanics calculations through the adaptive force matching method
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/6/10.1063/1.2965882
10.1063/1.2965882
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