Figure 2.1.1
This figure displays the potential energy surface (PES) for the reaction of chlorine radical with methane calculated at the (U)M06-2X/cc-pVTZ level of theory. Additional energy data for this system are shown in Figure 2.4.
On the reactant side we find methane and chlorine radical, that assemble into a loosely bound reactant complex.
Methane:
htrans_002.mol
#P M062X/cc-pVTZ int=ultrafine freq pop=npa htrans_002f M062X/cc-pVTZ opt=tight 0 1 C,0,0.,0.,0. H,0,0.6276073886,0.6276073886,0.6276073886 H,0,-0.6276073886,-0.6276073886,0.6276073886 H,0,0.6276073886,-0.6276073886,-0.6276073886 H,0,-0.6276073886,0.6276073886,-0.6276073886
The reactant complex between methane and chlorine radical:
htrans_005r.mol
#P UM062X/cc-pVTZ int=ultrafine freq pop=npa htrans_005rf UM062X/cc-pVTZ opt=tight 0 2 C,0,-2.170304231,0.0600607997,0.1450214417 H,0,-3.2030358796,0.1078109559,0.4836953931 H,0,-2.0490289443,-0.8052532999,-0.503825627 H,0,-1.9297281042,0.9680231622,-0.4035153141 H,0,-1.5164434985,-0.0314161934,1.0101824386 Cl,0,0.8056231669,-0.300530342,-0.7298486088
This is followed by the transition state for hydrogen atom transfer:
htrans_005ts.mol
#P UM062X/cc-pVTZ int=ultrafine freq pop=npa htrans_005freq UM062X/cc-pVTZ opt=tight 0 2 C,0,-0.0024505402,-0.0011777208,1.9154982209 H,0,-0.0294217144,-1.066387514,2.0986878656 H,0,-0.9122239353,0.553662862,2.0983456942 H,0,0.9321906209,0.5081466317,2.1052127265 H,0,0.00321482,0.0015343602,0.4435303875 Cl,0,0.008690749,0.0042213808,-0.9723853948
from where the reaction pathways follows down to the product complex:
htrans_005f.mol
#P UM062X/cc-pVTZ int=ultrafine freq pop=npa htrans_005ff UM062X/cc-pVTZ opt=tight 0 2 C,0,-0.0090422219,-0.0044449304,2.3847914637 H,0,-0.0347643448,-1.0793151783,2.4567374599 H,0,-0.9273610946,0.5547684376,2.4565649035 H,0,0.934058,0.5107380152,2.4643742701 H,0,0.0002954178,0.0003092085,0.1380150194 Cl,0,0.0055854313,0.0028113164,-1.1524968726
The product complex then separates into the two reaction products:
HCl
htrans_003.mol
#P M062X/cc-pVTZ int=ultrafine freq pop=npa htrans_003f M062X/cc-pVTZ opt=tight 0 1 Cl,0,0.,0.,0.1105226601 H,0,0.,0.,1.3894773399
Methyl radical
htrans_004.mol
#P UM062X/cc-pVTZ int=ultrafine freq pop=npa htrans_004f UM062X/cc-pVTZ opt=tight 0 2 H,0,0.,0.,0.0234694319 C,0,0.,0.,1.1 H,0,0.9323028199,0.,1.6382652841 H,0,-0.9323028199,0.,1.6382652841